Moroni's last recorded words include an exhortation to deny not the power or gifts of God. God worketh by power according to the faith of the children of men (Moro. 10:7). The gifts of God are given for the profit of man (Moro. 10:8). Among these gifts, he once again mentions the necessity of the ministry of angels (Moro. 10:14).
These gifts will never be done away as long as the earth shall stand, for the Lord is the same yesterday, today and forever (Moro. 10:19). Unbelief will be the only cause for their ceasing (Moro. 10:19, 24). If the gifts and power of God have ceased then there shall be none that doeth good, no not one (Moro. 10:25).
The Book of Mormon begins and ends with visions, angels, and the voice of God. These bookends reveal a primary theme that runs throughout its story. It is this: those who seek salvation, seek to know God and his Holy Son Jesus. A part of that search for God is that true messengers come to instruct in the way of life and salvation. They help prepare men for Christ. They provide the sought after further light and knowledge. They often declare repentance. It has ever been thus. The Book of Mormon is a witness that this is true. It is an invitation for all men to come unto Christ. It is a record of men who have walked the path.
Moroni spake by the power of the Holy Ghost, and with the tongue of angels. If we cannot understand his words it will be because we seek not, nor ask. If we reject his message we cannot be brought into the light, but must perish in the dark (2 Ne. 32:1-4). He exhorts us to seek for every good gift, not excluding the ministry of angels (Moro. 10:30).
To these angels is given power to seal men in their foreheads against the season which is to come (D&C 77:11). They have power to prepeare men and women for the church of the Firstborn (ibid.). They are a part of the process of sanctification. You cannot be sanctified except it be by the grace of God, and unless you partake of His power (Moro. 10:33).
The visitation of angels often seems unlikely and unbelievable to those who've not experienced them, and the messages shared by those taught by angels are often unpopular (Alma 21:5-6). The religious who are proud are inescapably found fighting against God's messengers. They would rather pride themselves in their sanctuaries, in their rites and culture (ibid). They are angered by the truth. This has been the pattern throughout history, anyway. It's remarkably similar in our day.
Eventually, God will show unto us all that the things this great prophet wrote are verily true (Moro. 10:29).