For somebody who doesn't bash gays, you seem to have a colorful choice of terms...
There are a whole lot of things society might like to do that are destructive of personal freedom and the notion that all men are created equal. Racial segregation was wildly popular in the South in 1950, but that didn't make it right.
The mechanism of having the state in the middle saying that certain people can be married and certain others can't is just corrosive. It does nothing for the sanctity of marriage and gives the people who want an expansive definition of marriage a mechanism to achieve their ends.
If you know you are destined to lose on a certain playing field, why play there? Why not get government out of the marriage business?