That's the libertarian stance. If the gov't had nothing to do with marriage and people were free to enter into whatever contract each party agreed to, we wouldn't be wasting time arguing about gay marriage.

Why should we have to "waste time"?

Gay people: We'd like to get married.

Government: Okay, here you go.

It's only because assholes go crazy about it that it's a problem.

Also, gay couples have been doing the "set up a bundle of contracts" thing for years. It's expensive and doesn't actually provide the same protections that marriage provides.