Mormon doctrine includes a Mother in Heaven. Some wonder why this doctrine is not emphasized; in fact, some claim it is suppressed and see this as evidence of misogyny in a patriarchal organization.
There appears to be archaeological evidence that ancient Judaism included the worship of Asherah. (It's tricky, because is the evidence of "true" ancient Judaism, or of apostate Israelites admixing paganism to their religion?) Some might claim, "It's not legitimate because Genesis doesn't tell us anything about Abraham, Isaac, or Jacob participating." However, dot, dot, dot....
What if...true worship of the God of Israel included worship of His wife? God sees how this quickly devolves into fertility cults and inappropriate doctrines. So when God's commandments for worship are re-revealed to Moses, there's no inclusion of His wife this time.
It makes sense to me. If I found out that I had students who were coming to office hours merely to lust over the pictures of my family I have on my desk, I'd stop having those pictures on my desk.
There's no reason to believe that the current extent of revealed religion is the full extent of God's gospel. The Law of Moses and the Sermon on the Mount are both religious systems revealed by a God who is "the same yesterday, today, and forever." And just because we say we live in "the fullness of times" doesn't mean the current structure is the final structure, either. (I believe this is what Dieter F. Uchtdorf was getting at when he said, "Sometimes we think of the Restoration of the gospel as something that is complete, already behind us.... In reality, the Restoration is an ongoing process; we are living in it right now. It includes 'all that God has revealed, all that He does now reveal,' and the 'many great and important things' that 'He will yet reveal.'")
This could explain why religions of neighboring Gentiles continued to be so attractive to Israelites, like early Jewish Christians who still practiced circumcision, or modern Roman Catholics who only attend Latin Mass; when a religion drops a requirement, there's a tendency to think, "I'll be an extra-good member and keep doing that old requirement."
Eventually, the post-exilic Deuteronomist reforms of Josiah uprooted all Asherah worship from Judaism, but that's not necessarily an indication that it is "wrong" knowledge, just that that group had shown they couldn't be responsible with the knowledge. (I don't know how I feel about Josiah's reforms. Was he right or wrong?)
Anyway, my point is that there can be very good reasons to keep some truths out of true religion without necessarily being the result of the church being a pious version of the He-Man Woman-Haters Club.