I just think it's funny how now we have the privilege to look back and say "we shouldn't have gone into Iraq" once we paid the price for not thinking this through all the way and half-assed an attempt to eliminate Al-Queda. Talk as much shit as you want, but people wouldn't have said a god damn thing about not sending troops when the tragedy was still fresh.
I don't mean to pile on, but....fuck it, I'm piling on.
LOTS of people said a LOT of god damn things about not sending troops. I was one of them. I went and spent my 27th birthday marching around Washington DC with a quarter-million other people. I went back up in Jan 2003 and damn near froze my ass off marching in protest. Maybe you forget, but we didn't go into Iraq until spring of 2003. A full 18 months after 9/11.
Your argument might carry a little more weight as regards Afghanistan -- we were in-country within a month or so of 9/11, and I didn't oppose that. I didn't relish the idea of a war, but it seemed a reasonable one -- war with al-Qaeda, and with the Taliban when they refused to cooperate or turn over al-Qaeda leadership enjoying their hospitality. That made sense.
Iraq was a cockeyed pile of bullshit from the get-go. No Iraqi involvement in 9/11, Saddam was not a fundamentalist, or a fan of al-Qaeda, or liked by al-Qaeda. There was no credible evidence that he was looking to do anything other than enjoy being a tinpot dictator and occasionally hurl invective at the US for his own domestic gain, a la Castro or Gaddafi or Kim Jong Il.
The fact that for so many people 9/11 became somehow, insanely, morphed into "We gotta go pay back Saddam for them hitting us on 9/11" was horrifying, maddening and dividing. I think that's the single moment that divided this country more than any other in the last 15 years, even more than Bush v Gore. It was when half the country looked at their neighbors, their friends, their own family and thought, "Holy shit, you people have lost your freakin minds!". And the other half looked back and thought, "Holy shit, you hate America!"
And everything since has been a deepening of that sanity/insanity divide.