WMD's or not, it's been a thorne in our ass since 89'. Since we didn't pull the trigger back in 91, it was an easy way to do so now. Saddam had been playing boarder games with Kuwait for the past 15+ years, and every time we sent out or ground pounders to greet him. Not to mention we took out both his sons to boot, which was a nice present.
Al-Qaeda doesn't hate the fact we have our noses in other business besides our own. They hate the fundamental beliefs of you, America, and those non-Muslim. Trust me, anyone of them would not think twice to murder you, your family, and anyone you know. Their hate I believe will be a non-ending hate. Everything about American and Western culture they despise with a passion.
One reason some things went to hell in a hand basket was thanks to politicians. Creating Rules Of Enguagement that were down right wrong and dangerous. Things could have been handled differently, I agree, but this is something that needs finished now. If not we could have a bigger mess 10+ years down the road again.