ArGee, we've back-and-forth'd on this in the past, so I don't expect you to accept my answer, but since you asked, here goes:
Americans like to see themselves as a fair-minded people. We've been taught since childhood that our country stands for opportunity and freedom that other nations can only envy. On the other hand, we also realize that equality of result cannot be handed out to those on the outs in our society, unlike the way things are done in socialist nations. We believe in the right of people unlike us to earn money, build up estates, and gain the respect of the community. But we don't necessarily want someone "different" from us being able to do it right next to us. We don't want our kids losing jobs because of affirmative action, we don't necessarily want minority groups climbing the ladder to prosperity in our neighborhood (especially while they're still on the lower rungs), and many people who want to see gays treated fairly don't want them using marriage as the name of the institution that gets them respectability.
The parallel for this was the treatment of black people in the century following the Civil War. Northern, white America was content to have fought and won the Civil War, while allowing "separate but equal" to be the law of the land. It satisfied the needs of the South, yet let Northern folks feel that at least black people had some opportunity. Our nation came face to face with the fact that there was not true equality for blacks in many places, as television brought the contrasting images of Martin Luther King and George Wallace into our living rooms in the 1960's. Today, the 24 hour news channels and the Internet bring images of gay people into our consciousness in a similar way, and while many people in the middle are comfortable with framing gay rights as a civil rights issue, they are uncomfortable with the all of a sudden (as they perceive it) rush from anti-discrimination laws, to gay marriage. It's like the days when people favored integration of schools, but didn't want their own kids bussed to the bad side of town.
Yes, gay marriage and civil unions are the same thing, but the people who say they are for CU, and not marriage, are just not quite ready to deal with the name issue. They still perceive gays as being significantly different from them to psychologically fall back on the "separate but equal" solution that Vermont has put on their radar screen. It appears (to them) to be a reasonable compromise, and people in what I call the "mushy middle" like compromise, rather than confrontation in dealing with political problems.
I have to disagree with everything you wrote but this. People truly believed blacks were subhuman, primarly thanks to Darwinism (see my tag line). Therefore they created "separate but equal" facilities like they have for dogs. Once we learned that there were no subhumans we became comfortable with full integration.
However, from what I can tell everywhere I look, those of us who consider homosexuality to be the evidence of a mental illness are strongly in the minority and have no say in society whatsoever. That's why the majority support these homosexual marriages. What I can't understand is their love affair with the word "marriage" that makes it wrong to use that word.
Nice liberal rant, by the way. I'd love to discuss affirmative action with you on an affirmative action thread.
Shalom.