Anti-discrimination laws do not just protect people for traits "they are born into." If that were the case, there would be no protection for the free exercise of religion, speech, or political opinion.

A straight, up-or-down, majoritarian vote on one group's rights is a scary thing. There are many groups that have been on the receiving end of majoritarian justice - Mormons, Chinese, Jews, and so on.

Mormons, in particular, have a short memory. Heck I'm 28, was raised Catholic, and was taught at church that Mormons were not Christian and were worse than pagans.