I’ve often wondered the same. Sadaam certainly was no angel, but his regime did stabilize the region.
Waging war with him over the stated purpose of getting his WMD’s just never made sense. It’s like cops giving notice to drug dealers they will be at their home in a few days to take all their drugs.
Sadaam tried to have W's daddy killed. Removing him was payback. The war had nothing to do with WMDs.
From Wiki
"April 13, 1993: Fourteen men believed to be working for Saddam Hussein smuggled bombs into Kuwait to assassinate former president Bush by a car bomb during his visit to Kuwait University several months after he had left office"