The truly serious issue on marriage in the US and elsewhere isn't on gay marriage as such but the issues implied in Justice Samuel Alioto's asking if four lawyers could marry.
The core system on marriage for the last few millennia centers on a sexually reproducing heterosexual couple. And this makes excellent sense if "The world must be peopled!" Over those millennia, society and then the State came to reward heterosexual marriage out of "pronatalist" policy: "People are the riches of a nation," and the idea was to increase the number of people.
Okay, but what about nowadays, when the world's been peopled and then some, with seven billion of us and counting, and a strain on the environment and on resources? If we want to be less "natalist," we want to encourage arrangements that are not sexually reproductive at all, or less so, but which might allow raising adopted children — plus providing companionship and economic advantage.
Soooo ... Mr. Alioto perhaps spoke better than he knew. We need to look at alternatives to reproducing couples and we need to rethink the incentives given to people to form reproducing couples and then reproduce. Such rethinking, and then acting, could include shifting tax burdens away from the childless and more toward those overly enthusiastic about reproduction, celebrating Childless People's Day once a year (or twice, to balance out Mothers' Day and Fathers' Day), toning down the praise of families and family values, noting that the nuclear family sucks for raising kids — putting too much burden upon one couple — and moving toward the old extended family.
I'm not sure I'd like to see four lawyers raising a puppy, let alone children, but we do need to start talking about allowing such relationships the privileges and advantages of married folk.
And with that we can start our serious arguments over marriage: the mostly economic ones that will seriously question who gets what, just how much, and for how long and for how many offspring.