Republicans represent the wealthier base, so they better afford to market themselves as the more appealing option to moderates, even when they would be better off choosing someone else. Also, they've got a lot more "creative talent" when it comes to presenting an image, and this simplicity fits in with the simplicity of their policy.
Kind of the problem with Democrats is that they are so ineffective in terms of promoting their policy, they pull themselves further to the right to pander and then end up (1) standing for very little and (2) leave a whole base of progressives without a voice. About a third of Americans are against same-unions, about a third are for same-sex unions but against same-sex marriage (actually the smallest group), and about a third are for allowing same-sex marriage. Republicans almost all present the first, most Democrats represent the the second, and a few Democrats actually stand for the third. But sort of the thing about (2) is that since they don't have representation, this large group of people end up being painted as "extreme," even though they're about as common as those who would ban same-sex unions, and they'd be about the majority (or the majority outright) in a number of developed countries.
Oh wait, this thread is supposed to be about Abu Ghraib.
The more I hear about this war, the more important it seems to put key people of the Bush administration on trial for war crimes.