Hey Bob, hindsight is 20/20. Now we're pretty sure there are no WMD, but if you had been President in the post-9/11 world, would you have been willing to take a chance based on the evidence you saw at the time?
Ignore all the politics for a minute. Of course the Democrats are going to accuse Bush of misleading them--what would you say if you once voted for something you now find was a mistake? It won't fly politically to say "Oops, I'll be more careful next time." Part of the principal of government checks and balances is that Senators are supposed to be able to get access to intelligence information if they feel the administration is misleading them. Did those who voted for the war just blindly believe everything they were spoon fed?
Again, hindsight is 20/20. We'll never know what would have happened if we'd waited on the inspectors report. But one possible outcome that Bush must have been considering is this: the inspectors find nothing, and France/Russia lead a charge to drop sanctions. Today we might have been looking at a world where Saddam & sons were more powerful than ever: no sanctions, huge oil wealth and control, end of no-fly restrictions, and full speed ahead on a quickly reconstituted WMD program.