There are oh-so-many vital ideas that oh-so-many people do not get. In general, I will say that the problem of grossly undervaluing the greatest of gifts is endemic among all people, and errors in appraisal of value (how much is possible and where it is found) may well be the single greatest obstacle to eternal life for those alive today, if not throughout all time.
Specifically to this instance:
30 For behold, [angels] are subject unto him, to minister according to the word of his command, showing themselves unto them of strong faith and a firm mind in every form of godliness.
31 And the office of their ministry is to call men unto repentance, and to fulfil and to do the work of the covenants of the Father, which he hath made unto the children of men, to prepare the way among the children of men, by declaring the word of Christ unto the chosen vessels of the Lord, that they may bear testimony of him.
32 And by so doing, the Lord God prepareth the way that the residue of men may have faith in Christ, that the Holy Ghost may have place in their hearts, according to the power thereof; and after this manner bringeth to pass the Father, the covenants which he hath made unto the children of men. (Moroni 7)
Q: Who are "the residue of men"?
A: Anyone who has not yet seen angels.
Q: How do "the residue of men" have faith in Christ?
A: Through the ministry of those who can, who have sufficient faith to repent when they are told to by the angels that visit them.
Q: How much more faith does it take to receive angels and repent because of their message than it does to respond to the example of a mortal man who already has?
A: A lot. Reread Alma 13.
Q: Is it possible for the world to become so faithless that angels cease ministering to men?
A: Yes, when the people are particularly wicked, God ceases to send angels:
36 Or have angels ceased to appear unto the children of men? Or has he withheld the power of the Holy Ghost from them? Or will he, so long as time shall last, or the earth shall stand, or there shall be one man upon the face thereof to be saved?
37 Behold I say unto you, Nay; for it is by faith that miracles are wrought; and it is by faith that angels appear and minister unto men; wherefore, if these things have ceased wo be unto the children of men, for it is because of unbelief, and all is vain. (Moroni 7)
Q: What does God do in such a case to continue to provide the lifeline of his light to the world?
A: He sends down the spirit of a man righteous enough to repent based solely on the written word preserved to that point, following the pattern and example of Jesus, who did the same.
1 Behold, the LORD’s hand is not shortened, that it cannot save; neither his ear heavy, that it cannot hear:
2 But your iniquities have separated between you and your God, and your sins have hid his face from you, that he will not hear.
3 For your hands are defiled with blood, and your fingers with iniquity; your lips have spoken lies, your tongue hath muttered perverseness.
4 None calleth for justice, nor any pleadeth for truth: they trust in vanity, and speak lies; they conceive mischief, and bring forth iniquity.
5 They hatch cockatrice’ eggs, and weave the spider’s web: he that eateth of their eggs dieth, and that which is crushed breaketh out into a viper.
6 Their webs shall not become garments, neither shall they cover themselves with their works: their works are works of iniquity, and the act of violence is in their hands.
7 Their feet run to evil, and they make haste to shed innocent blood: their thoughts are thoughts of iniquity; wasting and destruction are in their paths.
8 The way of peace they know not; and there is no judgment in their goings: they have made them crooked paths: whosoever goeth therein shall not know peace.
9 Therefore is judgment far from us, neither doth justice overtake us: we wait for light, but behold obscurity; for brightness, but we walk in darkness.
10 We grope for the wall like the blind, and we grope as if we had no eyes: we stumble at noonday as in the night; we are in desolate places as dead men.
11 We roar all like bears, and mourn sore like doves: we look for judgment, but there is none; for salvation, but it is far off from us.
12 For our transgressions are multiplied before thee, and our sins testify against us: for our transgressions are with us; and as for our iniquities, we know them;
13 In transgressing and lying against the Lord, and departing away from our God, speaking oppression and revolt, conceiving and uttering from the heart words of falsehood.
14 And judgment is turned away backward, and justice standeth afar off: for truth is fallen in the street, and equity cannot enter.
15 Yea, truth faileth; and he that departeth from evil maketh himself a prey: and the Lord saw it, and it displeased him that there was no judgment.
16 And he saw that there was no man, and wondered that there was no intercessor: therefore his arm brought salvation unto him; and his righteousness, it sustained him.
17 For he put on righteousness as a breastplate, and an helmet of salvation upon his head; and he put on the garments of vengeance for clothing, and was clad with zeal as a cloke. (Isaiah 59)
2 Wherefore, when I came, was there no man? when I called, was there none to answer? Is my hand shortened at all, that it cannot redeem? or have I no power to deliver? behold, at my rebuke I dry up the sea, I make the rivers a wilderness: their fish stinketh, because there is no water, and dieth for thirst.
3 I clothe the heavens with blackness, and I make sackcloth their covering.
4 The Lord God hath given me the tongue of the learned, that I should know how to speak a word in season to him that is weary: he wakeneth morning by morning, he wakeneth mine ear to hear as the learned.
5 The Lord God hath opened mine ear, and I was not rebellious, neither turned away back.
6 I gave my back to the smiters, and my cheeks to them that plucked off the hair: I hid not my face from shame and spitting.
7 For the Lord God will help me; therefore shall I not be confounded: therefore have I set my face like a flint, and I know that I shall not be ashamed.
8 He is near that justifieth me; who will contend with me? let us stand together: who is mine adversary? let him come near to me.
9 Behold, the Lord God will help me; who is he that shall condemn me? lo, they all shall wax old as a garment; the moth shall eat them up.
10 Who is among you that feareth the Lord, that obeyeth the voice of his servant, that walketh in darkness, and hath no light? let him trust in the name of the Lord, and stay upon his God. (Isaiah 50)
14 Fear not, thou worm Jacob, and ye men of Israel; I will help thee, saith the Lord, and thy redeemer, the Holy One of Israel.
15 Behold, I will make thee a new sharp threshing instrument having teeth: thou shalt thresh the mountains, and beat them small, and shalt make the hills as chaff.
16 Thou shalt fan them, and the wind shall carry them away, and the whirlwind shall scatter them: and thou shalt rejoice in the Lord, and shalt glory in the Holy One of Israel.
17 When the poor and needy seek water, and there is none, and their tongue faileth for thirst, I the Lord will hear them, I the God of Israel will not forsake them.
18 I will open rivers in high places, and fountains in the midst of the valleys: I will make the wilderness a pool of water, and the dry land springs of water.
19 I will plant in the wilderness the cedar, the shittah tree, and the myrtle, and the oil tree; I will set in the desert the fir tree, and the pine, and the box tree together:
20 That they may see, and know, and consider, and understand together, that the hand of the Lord hath done this, and the Holy One of Israel hath created it.
21 Produce your cause, saith the Lord; bring forth your strong reasons, saith the King of Jacob.
22 Let them bring them forth, and shew us what shall happen: let them shew the former things, what they be, that we may consider them, and know the latter end of them; or declare us things for to come.
23 Shew the things that are to come hereafter, that we may know that ye are gods: yea, do good, or do evil, that we may be dismayed, and behold it together.
24 Behold, ye are of nothing, and your work of nought: an abomination is he that chooseth you.
25 I have raised up one from the north, and he shall come: from the rising of the sun shall he call upon my name: and he shall come upon princes as upon morter, and as the potter treadeth clay.
26 Who hath declared from the beginning, that we may know? and beforetime, that we may say, He is righteous? yea, there is none that sheweth, yea, there is none that declareth, yea, there is none that heareth your words.
27 The first shall say to Zion, Behold, behold them: and I will give to Jerusalem one that bringeth good tidings.
28 For I beheld, and there was no man; even among them, and there was no counsellor, that, when I asked of them, could answer a word.
29 Behold, they are all vanity; their works are nothing: their molten images are wind and confusion. (Isaiah 41)
Q: How much more faith does it take to "receive angels" by repenting through reading and obeying what is written in the scriptures versus needing to receive a literal visitation from an angel?
A: A lot.
Q: What is the effect of accomplishing something through greater faith versus lesser faith?
A: Whenever a greater price is paid, the justice of God grants greater blessing upon the one who pays it. Because all attributes of God co-occur, the greater the faith exercised, the more likely the one exercising it will transfer the boon he receives to the benefit of those who did not pay the price.
Q: How many people on this planet would repent without first having a living example?
A: I don't know, but because someone has, no one will ever be able to again in this creation. From now until the end, there will be living people who are examples of sinlessness. Some measure of people, and perhaps all but one, need a living example before they will repent. Consider this honest email I received three months ago:
"For me the reasons you have shared on the need for full repentance have not been refuted; however, if you didn't put yourself forward as an example of sinlessness I would probably reject them anyway, given that I am unaware of anyone else making a similar credible claim. I am increasingly grateful for your example and your sacrifice. You have convinced me that the love of God exceeds anything I have ever imagined to provide such motivation."
As servants of the Most High, we do not do what we do for credit, because he doesn't do what he does for credit. He does what he does so that man can have greater joy than he did, and that is the motive of his servants, too. However, since joy comes from value, and value from cost, part of the ministry of joy is helping people understand the price that has been paid for them.
5 ...the love of God is shed abroad in our hearts by the Holy Ghost which is given unto us.
6 For when we were yet without strength, in due time Christ died for the ungodly.
7 For scarcely for a righteous man will one die: yet peradventure for a good man some would even dare to die.
8 But God commendeth his love toward us, in that, while we were yet sinners, Christ died for us. (Romans 5)
40 And Jesus answering said unto him, Simon, I have somewhat to say unto thee. And he saith, Master, say on.
41 There was a certain creditor which had two debtors: the one owed five hundred pence, and the other fifty.
42 And when they had nothing to pay, he frankly forgave them both. Tell me therefore, which of them will love him most?
43 Simon answered and said, I suppose that he, to whom he forgave most. And he said unto him, Thou hast rightly judged.
44 And he turned to the woman, and said unto Simon, Seest thou this woman? I entered into thine house, thou gavest me no water for my feet: but she hath washed my feet with tears, and wiped them with the hairs of her head.
45 Thou gavest me no kiss: but this woman since the time I came in hath not ceased to kiss my feet.
46 My head with oil thou didst not anoint: but this woman hath anointed my feet with ointment.
47 Wherefore I say unto thee, Her sins, which are many, are forgiven; for she loved much: but to whom little is forgiven, the same loveth little. (Luke 7)