When Bush's inner circle first really came to grips with the threat of terrorism, they did so in a state of shock -- a bad state in which to develop a coherent response. Fearful of new attacks, they authorized the most extreme measures available, without assessing whether they were really a good idea.
I believe this zeal stemmed in part from concerns about the 2004 presidential election. Many in the White House feared that their inaction prior to the attacks would be publicly detailed before the next vote -- which is why they resisted the 9/11 commission -- and that a second attack would eliminate any chance of a second Bush term. So they decided to leave no doubt that they had done everything imaginable.
No surprises here. Richard Clarke has been a voice of sanity and reason since 9/12.