I agree with you to an extent. I've said many times that I wouldn't have started the Iraq war when bush did. But the issue is that it was started, we had troops on the ground, and when you are faced with a choice between giving up, or wining. I tend to assume we will be better off wining, than losing.
And we won, obviously. Despite this demagogue its clear Nuri is our guy in Iraq, the Iraqis are happy, and we can move on now.
All things considered, it wasn't the worst mistake in the history of American interventionist foreign policy, (that would be the retreat from Vietnam in my opinion)