The problem is without a commitment to stay in Iraq for at least 20 years, once we left it would go to pot. There are no guarantees that future administrations wanted to stay in Iraq, and this fact should have been given more consideration before going in.
I think even if Obama had come in under such circumstances---which he might not if Bush had done the above---even he would have lacked the support to pull out. But, as I say, we'll end up paying for that real estate all over again.