I'm troubled with the reasoning that "good intentions" can serve as a justification here. What really matters in the end are the results, and the results are pretty tragic. (All this assuming Bush's motivations were of a humanitarian nature, something I'm not convinced about at all). And going to war on a whim (and given the lack of immediate threat and other options being far from exhausted, that's what happened then) is not justified, just as plunging head on into such an enterprise based on inconclusive intelligence is not justified as well. And it's pretty clear the administration wasn't just basing its assumption on faulty intelligence, it was actively pushing the course from the beggining.
Is Saddam breaking a ceasefire agreement every day for 12 years not a good enough justification?
I would say we waited too long, because clearly Saddam was walking all over us.