Why Creationism?

From Distributed Republic a couple of years ago:

I've been having a bit of an ID/Evolution tussle with Bob Murphy here and here, and a question just occurred to me: What exactly is it the purpose of Intelligent Design/Creation Science?

Yes, yes, the obvious explanation is that theists want God taught in the science classrooms. But doesn't this violate a central tenet of theism? Namely, don't all theists have to account for the hiddenness of God? That is, if God exists, why doesn't God make its own existence obvious, and eliminate all of the time wasted (and sins committed) as a result of reasonable doubt?

Most versions of theism that I have encountered give a similar answer to this question: the hiddenness of God is a test of faith, for which believers will be rewarded. Open, obvious evidence for God's existence would remove a significant element of free will - we would not be believing because we choose to believe, but because we must believe.

But if that's the case, then why the urge to prove, scientifically, that God is in the gaps? Why are IDers/Creationists looking for, not just any evidence, but scientific evidence, in the form of irreducible complexity as an argument for the existence of a designer?

If God really did exist, why would God provide complex, statistical, scientific evidence for its own existence only in the micro-world of biochemical processes, and not instead, say, host his own public access television show called Jesus and Pals? Are microbiologists more deserving than the rest of us to bask in the knowledge and glory of the Divine? Or does God want us all to give up our day jobs and become microbiologists?