California is the ideal place to experiment with a fundamental redefinition of society's foremost building block, marriage. After all, there are only 38 million people in California, Californians are famously level-headed and rational, and Californians don't have any influence over the media. So, if it turns out a generation from now to have been a bad idea, no harm done!
My concern, since 2001, is that more gay men would be interested in getting married (i.e., in a theatrical ceremony) than in being married (i.e., sexual monogamy). We're talking about some awfully flamboyant folks: Gay Pride parades could more honestly be renamed Gay Narcissism parades.
So that the long term danger from gay marriage would likely be to make more straight guys reluctant to go through the already punitive process of getting married. Being the groom in a wedding ceremony is a pretty uncomfortable thing already, but at least it's a guy thing, not a gay thing. As John Derbyshire quoted me in 2003:
On the other hand, there's a process of gay ghettoization that goes on when straight men recognize that some institution is disproportionately attractive to male homosexuals. Broadway, for example, has gone from a popular national institution to a largely gay ghetto in recent decades. It's hard to get a serious discussion going of this since nobody wants to be accused of being homophobic, but I see it everywhere. I don't think marriages will be popular enough among gays to start this process, but I worry that weddings will be. It wouldn't take much to get the average young man to turn even more against participating in an arduous process that seems alien and hostile to him already. If some of the most enthusiastic participants become gays, then his aversion will grow even more.
The subheadline in the LA Times today reveals a campaign by gay leaders (and, no doubt, their allies in the media) to keep the ceremonies toned down until after the November California initiative vote:
"Flamboyant images from same-sex ceremonies, activists say, could be used by opponents to convince California votes that gays and lesbians shouldn't have the right to marry."
