I don't think it ever was about WMD. It certainly wasn't about 9/11 - 18 of the 19 hijackers were from Saudi Arabia, but we consider them our "friends." Why? Because they have oil we want. And someone's oil friends make money from them.
I think it was about someone's desire to make the world democratic. Check out
http://www.newamericancentury.org/ Take a look at the signers at the bottom of the Statement of Principles. They include Rumsfeld, Cheney and Wolfowitz.
Who stands to benefit from an extended war? The military-industrial complex. If you want to make money for your friends, you certainly wouldn't want to end the conflict in 3 weeks and head home. You need to keep up the demand for arms, vehicles, and everything else the military needs to function. Follow the money.
I think we need to get the F&%$ out of there immediately and let the Iraqi government sink or swim on its own merits. This certainly hasn't been worth the lives of our young men and women and isn't worth even one more life. If the animals want to annihilate each other, at least it won't be our people getting killed.