Because the bitterest contradiction of all may be that this war was waged—first and foremost—to save face after the humiliation and suffering of September 11. It was meant to inspire awe in the Arab and Muslim world, as former CIA operative Marc Reuel Gerecht and others insisted it should be. And in that it truly has failed. Every day we look weaker. And the worst news of all it that it’s not because of what was done to us by our enemies but because of what we’ve done to ourselves.
In the end, this was the reason why most of the warbloggers were so in love with this endeavor. Afghanistan just didn't satisfy their bloodlust, so they wanted to go punch someone else. Anyone else. The Neocons were on record all over the place (pre and post 9/11) discussing the need to project American might through a major military conquest so that nations would tremble before us. It isn't an agenda I'd sign up for, but aside from that the the obvious problem with is that if it fails - and regardless of what eventually unfolds in Iraq it already has failed - the consequences aren't desirable. I may not want projecting our military might to be the cornerstone of our foreign policy, but I sure as hell don't want projecting our weakness to be it either.
On a related note, the military is going to have a big retention and recruiting problem...