Woohoo! I get another first crack at ehBeth's polls!
The saddest thing about this whole ordeal is that many of these problems were noted before the war. See
http://www.freep.com/news/nw/iraq12_20030712.htm (providing an incomplete list of State and CIA memos that were discarded in favor of the DoD's now debunked optimism). The new, activist foreign policy promoted by Bush had significant cache among foreign policy aficionados prior to his bumbling in post-war Iraq. Many of the members of the largest pre-war reconstruction study -- the "Future of Iraq" group (a combined agency group headed by State) -- favored an active approach even as they cautioned against the DoD's misplaced optimism. As far as I can tell, the administration intentionally blinded themselves from their own foreign policy and intelligence agencies.
A more intellectually curious approach -- one that tolerated dissenting voices and considered base-level intelligence in addition to top-level ideology -- would not have necessarily concluded that this war was a 'bad' idea. I remain compelled by an active foreign policy (Iraq not being a good example of how such a policy works), but this administration's aversion to dialogue and debate have made the war ten times more difficult than it needed to be.
Why wasn't anyone listening? They're still not listening despite the clear fact that the dissenters were right about reconstruction. The same voices that expressed caution about the ease of reconstruction have left or been removed from State and CIA, while those that pushed the cakewalk story are still calling the shots at the DoD. It's frustrating for someone that hoped that the Bush administration could breath new life into American foreign policy.