How anyone could see BY's marriage to teenagers as young as 15 as an older adult male, and still think he was called of God is another good take on the brainwashing Mormons undergo in order to accept such a horrible reality.
I don't think it's simple lust for every Mormon who believes in polygamy. Religion can make people do strange things. I heard there was actually a man in UT who thought God had told him to sacrifice his son like Abraham was told to sacrifice Isaac, only he went through with it. I don't think he wanted to do this because he didn't like his son. I think he really thought God told him to do this.
Just like I don't think that Moslems are simply blood thirsty killers. I think they really believed that God told them to crash their planes into the towers. But people still desire to find meaning in life and know the truth. So religion will always be here. Unfortunately we're going to mess some things up in our search for peace and truth.