Seems to me that Iraq didn't become our national obsession until the effort to track down Osama Bin Laden ran out of gas. Saddam is more easily located, so he became the new bogey-man. Lest we forget, Bush was making macho claims, within days of 9/11/01, that OBL was just about within our grasp. "We're gonna get him," I believe the words were.
But we didn't, so it's all about Saddam now. The same tough-guy rhetoric from our Chief. It's so reassuring...