So your argument is:
1. The state usurped the institution of marriage from the Church, where it rightfully belongs
2. The state devalued the meaning of marriage
3. The state should continue to license this activity
That doesn't make a lot of sense to me.
That's not part of my argument. So far, I don't hold the state responsible for the devaluation of marriage. Let them start passing laws trying to redefine it (e.g. gay marriage, and I'll quickly change my opinion.