durasell,
I think you nailed it right on the head. I think a lot of the debate is not driven on the rational merits of the action, but on the emotional buttons it pushes.
Well yeah. Talk to gay guys of a "certain age" and you'll find a lot of them were tossed from their homes either after high school or college. I had a couple gay friends who had fathers who tried to beat the gay out of them...closed fists and workboot beatings (Not a lot of success with that method). And then tossed out. Basically they were purged from their communities.
Anyway, this thing goes back down to the states. Some states ban "gay marriage" and some adopt it through vague legality or outright. And everyone gets to go on about their lives.
In fact, expanding the meaning of marriage can not be constrained by sexuality at all. For instance, if the liberty interest in question is as Justice Kennedy says, a transcendent thingamabob based on love then certainly one can "marry" one of his or her grandkids before he or she checks out so the grandkid gets social security survivors benefits for the rest of his or her life. And that little scam can then be repeated in perputuity, or at least until the trough runs dry when everybody catches on.
Likewise and two or more people can "marry" to get their sticky little fingers into the public trough and then should be able to do so with impunity so long as they profess the love of their temporary spouse??? and liberty.
I mean what the hell, what's good for one is good for all.