In related news, Butler Shaffer is puzzled as to why gay-marriage advocates want to have the state certify [their] relationships with others as opposed to just perform[ing their] own ceremony of marriage without getting the states approval.
The answer, obviously, is that the state imposes special burdens on couples who dont marry in the approved manner. If, for example, you want to be able to visit your hospitalised spouse, or want to marry a noncitizen and not worry about their being deported, only a governmentally approved marriage will do.
It may be asked why civil unions, rather than something explicitly called marriage, wouldnt be good enough for such purposes. Of course most opponents of gay marriages oppose civil unions too; but in any case, words matter. Suppose that all government documents used the n-word to refer to blacks, but didnt otherwise treat them differently from anyone else. Wouldnt blacks still have a basis for complaint? (I owe this point to Jacob Levy.)