The reason we went to war is because he was violating his agreement with the 1991 cease-fire resolution. It wasn't the US's responsibility to prove Saddam didn't have any WMDs. That was his responsibility. If Saddam would've given the US unlimited access and definitive proof that he destroyed all WMD and their programs it would've been very hard for the US to invade. Besides, just because we didn't find the
in Iraq doesn't mean he never had them in the first place. He had three months to move them out of country and we know they probably went to Syria.
In the end we wanted proof and all Saddam gave us was promises. I guess Saddam's promises were good enough for some people. Example, Charles Mason is up for parole. He promises he won't kill anyone when he is released. Absent any other evidence other than his history, would you believe him?