Not sure I see your point here. It still remains true that this was held as a revelation from God having its basis in the Book of Mormon,correct? For whatever reason, this revealed truth changed.
The basis for this is actually not in the Book of Mormon. The Book of Mormon does include the concept of skin color being changed as a curse from God, bit the ose of the darker races in the Book of Mormon were not denied the Priesthood. Mormons believe them to be ancestors of Native Americans, North and South America, and of the Polynesians.
The LDS belief about Priesthood attributes better to things in the Book of Moses, the Book of Abraham (in the LDS book of scripture called “The Pearl of Great Price” and in the Bible as understood within the light of those and in Joseph Smith’s transliteration of it.
They believe that Cain entered into a covenant with the Devil, in which the Devil taught Cain that he could murder and get gain. See, the whole thing about God being satisfied with Abel’s offering was that Abel was more greatly blessed, hence more prosperous. When Cain was not as greatly blessed, he wanted what Abel had, and the Devil told him how to get it.
The Mark on Cain was that his skin was turned Black (though I have been told recently that the LDS Church no longer teaches this, either – can’t verify it, but the record speaks for itself) . Part of the curse was that he and his ancestors would not be permitted to hold the Priesthood untill the curse was removed, which would take a revelation from God.
There has been a lot of discussion and rhetoric, speculation often stated from authoritative individuals, but not from “seats of authority” like official statements, as to what the reason was – and delving into those would be an unneccessary tangent. The official reason for the ban was that God has never given a reason, and as God he does not have to. That has been consistent. Even Joseph Smith, despite what people specualte, said no more about it than I have said here.
The important thing is that it was also doctrine that someday black people would be allowed to hold the priesthood, and get all of what they consider the blessings associated with it – being able to serve missions, receive tample ordinances(sacraments) and marry in the temple for time and all eternity. The LDS Church always taught that the day would come when it would be allowed.
I can tell you that the Sunday before the “revelation” allowin this was announced, I heard some discussioon on it, and everyone – including at the time “Bruce’s Bible” said it would not happen until the 1,000 years of peace following Christ’s return.
Like I said – it reached a point where the Church could not grow in other countries without it, and where one segregationist holdout remained in the Quorum of the Twelve, and he was on his deathbed, This was one change they said would happen someday, so the change is actually a consistencly.
Polygamy is another story form standard LDS reasoning – nothing in most LDS dialogue suggested it would be temporary in the restoration. They resisted abandoning it until they had no more legal recourse. The fact is the Book of Mormon makes it clear that God despises polygamy, and only justifies it when he specifically commands to " raise up seed" but only then.
So, allowing universal male membership in the priesthood is actually filfillment of prophecy – it was always expected to happen someday. Abandonong ht practice of polygamy is specifically related to the laws against it – in this cae the LDS god changes hos mind because of the laws of men.
Lie I said, that concept applied during the major early persecutions would keep people from marytrdom rather than encouraging them to accept it.
Mormons should not find this offensive, since their position affirm – even if it does not spell it out – that the Christian martyrs of the first three centuries could not have been real Christians anyway.