This piece nicely explains away the incompetence dodge:
Part of the effort to pull the wagon of conservatism out of the ditch into which Bush piloted the country is going to be an effort to deny that George W. Bush was a real conservative. In reality, Bushism should be understood as the highest form of conservatism. In particular, the High Bushist years of 2001-2006 represent the only time that the post-war conservative movement has had total control over the federal government. If the practical consequences of pre-Bush conservatism were less disastrous, that’s largely because conservative political power was more constrained in those earlier eras.