Bit early to draw that conclusion, I think. Give it a couple of decades. (Someone recently quoted Zhou En Lai on the French revolution - wise words.)
In addition to not knowing what the future holds, there's also the 'counterfactual history' problem - we know what happened because Bush decided to move, but we have no idea what would have happened had he not moved.
This is a pretty reasonable countpoint, but I would like to point out something. If you set a sufficiently distant horizon, then pretty much anything can work out. To give an absurdly exaggerated example, I could claim that American slavery was ultimately OK because look how great America is now — and we don't know how things might be different if we hadn't had it.
I could go on at great length about this, talking about how US troops in Saudi inflamed Osama, about how Saddam had an appetite for weapons, etc, etc but again, that's looking back, not too useful an exercise.
Thanks for putting it that way, because I think that's really what I'm trying to get at. There's a lot of water under the bridge, and we have to take things as they are now. Unfortunately, that includes some political realities that we need to face if we're going to recover from this setback.