For me, it comes down to Iraq's behavior. Iraq gave little reason for others to believe its statements that it had ended its prohibited weapons and missiles programs. It was still importing prohibited materials (as the aluminum tubes were even if they were only for rockets) in contravention of the UN sanctions. It never, as the UN demanded, fully accounted for the materials it claimed to have destroyed. It was still playing games with the inspection process - not giving a full accounting, threatening scientists with death if they were interviewed, etc.
Correct me if I'm wrong, but I thought Iraq was allow to have rockets provided they were of a limited range?
In any case, I totally agree with you on this argument. Iraq was playing schenigans.
What bothers me though, is the schenigans that others have played. Someone forged those Niger documents. Like it or not, US official did claim that Iraq was 6 months from having nuclear weapons.