The real reason I think that creation science (and the more marketable offshoot known as "intelligent design") are being promoted so heavily is actually quite simple: to spread the word of Christ into public schools. Proponents of these movements feel that Jesus gets short shrift in science class, so they find a way to make religion look science-y.

It's got nothing to do, IMHO, with any tension between the Bible and science itself -- it's all about getting more Jesus into the classroom. For Christians, that is its own reward -- they are commanded to spread the word of Christ, and by getting it into science curricula, they've succeeded in doing that.