Like the JWs, some Mormons question their beliefs and leave because of absurd teachings.
I spoke to some Mormons regarding their tea and coffee ban. They did not know why it was banned and it wasn't the caffeine as they are allowed chocolate and coke. However, they said that their leaders had been given this instruction from God so they strictly followed it.
I talked to my hem about polygamy and they said that at one time it was allowed for a short period, they didn't know why but they trusted that God had his reasons for it. God conveyed this to their leaders.
My understanding is that they don't vote on these matters but Mormons are taught that they are conveyed to the leaders from God. In JW terms, they are inspired. With such power, it is surprising that they don't change more things.
I wonder if they'll get rid of their magic underwear as well. After all they wouldn't want to get stubborn coffee stains on them.