Since the beginning, God has called prophets. The first man - Adam - was a prophet, a holy man of God, and one authorized to act in God's name. Other prophets were called after Adam, men such as Enoch, whose city Zion fled, Abraham, Isaac, Jacob, and Moses. Then came prophets such as Isaiah, Jeremiah, Lehi, Alma, Mormon, and many others. Finally came the greatest prophet - John - and Jesus Christ. Jesus established His church after His resurrection with Peter as president and James and John as counselors. This establishment of the Lord's church did not last long. The vineyard became corrupted and the priesthood authority and keys were taken from the earth. For about 1800 years, the Lord's authority was not found on the earth (at least in the Old World; the priesthood lasted until about 400 AD in the Americas). One spring morning a boy sought an answer to a question about which church to join. He retired to a secluded grove of trees near his home and tried to pray vocally to God. As mentioned previously, Joseph's prayer was interrupted by Satan, who sought to kill him. Joseph was saved by the appearance of God, the Father, and then Jesus Christ. They spoke with Joseph. He was called as the Lord's prophet - a modern Abraham - father to a new dispensation. Over time, Joseph received the authority and keys necessary to administer the Lord's affairs on earth through His church. Once again the Lord's authority and church were found on the earth.
It has always been the Lord's will and work to use prophets. Amos wrote, "Surely the Lord God will do nothing, but he revealeth his secret unto his servants the prophets" (Amos 3:7). This is the Lord's pattern. Moroni wrote: "O all ye that have imagined up unto yourselves a god who can do no miracles, I would ask of you, have all these things passed, of which I have spoken? Has the end come yet? Behold I say unto you, Nay; and God has not ceased to be a God of miracles.... And if there were miracles wrought then, why has God ceased to be a God of miracles and yet be an unchangeable Being? And behold, I say unto you he changeth not; if so he would cease to be God; and he ceaseth not to be God, and is a God of miracles. And the reason why he ceaseth to do miracles among the children of men is because that they dwindle in unbelief, and depart from the right way, and know not the God in whom they should trust." (Mormon 9:15, 19-20).
God is a God of miracles. God changes not. He appeared to Joseph Smith in our day just as He did to prophets of old. He does mighty wonders today, just as He did in ancient times.
For those who might not believe that we need prophets let me ask a hypothetical question. What if we needed someone like Noah today? Would God call someone to be a prophet or would he simply allow all of us, proverbially, to drown? Why if God called prophets in Biblical times would He not call them today? Do prophets become unnecessary with the times? We live in a modern society so there is no need for prophets? Did God speak all He needed to speak unto us in the past so there is no need for Him to reveal more to humankind?
I find all those explanations insufficient. God is the same yesterday, today, and forever. He continues to speak to prophets today. Their words and revelations provide direction and comfort. However, they are more than just comforters and tour guides - they hold the Lord's priesthood and the keys that authorize the use of that priesthood. They administer the affairs of the Lord here on earth. They are in charge of His church and are responsible not just for the members of the church but also for all humankind. They are responsible to oversee and direct the missionary efforts of the church. They are as laborers in the vineyard or shepherds to a flock. The roles of prophets (and seers and revelators) and apostles are not honors taken by those with those responsibilities. All were called of God as was Aaron (see Hebrews 5:4). The honor and glory of the callings all belongs to God, for they direct His church.
Again I ask, what if the Lord needed to tell us something important today like He told the world through Noah or Jonah or Moses? Would He leave us to our own devices or would He call a prophet who would speak His words and do His work? I testify that God does speak to prophets today. He does not lead us without a guide. He does love us as much as He loved His children in ancient days. Satan is real and God is real. Prophets of God have been called to counter the prophets of Satan. The prophets of Satan are myriad, the prophets of God are few but the Lord's prophets have His power and His authority. They direct His church, even The Church of Jesus Christ of Latter-day Saints. Christ's church is on the earth. We can know God's will and plan for us by listening to His prophets.