I never understood why he didn't.
Bush has strengths and weaknesses like anyone else. His biggest mistake was not to clean out ALL the known clintonoids and deadwood from ALL parts of the Executive branch. He did a good job with the UN contingent but left almost everything else the way he inherited it.
Bad mistake.
He was badly handicapped by the Chad Wars and clinton's refusal to work with his transition team. But that shouldn't have stopped him, it just should have slowed him down a bit at the start.