Well, for child custody, immigration rights, inheritance rights, rights of who makes life and death decisions when you're incapacitated, etc. Not to mention health care sharing, tax benefits, etc. There are a *lot* of reasons to be married to someone from a purely legal perspective. I just would like to see the legal rights separated from the societal rights. (And moved to a civil union sort of thing that didn't involve the idea of "sleeping with" the other person. Heck, I could even see advantages of marriage like rights with siblings, provided that they were who you *wanted* to be legally tied to for various reasons.)