Okay let's pull them all out now.
How many days/weeks do you think that's going to take?
Do we just drop everything and run and leave weapons and supplies behind for the insurgents and other bad guys to inherit?
And what about the Iraqis whose country is a smashed and stinking hole who still count on us to provide some semblance of order (as corrupt as that order might be)?
Regardless of who is at fault for the mess should we just bail out?
I can think of several radical countries who would just love to come in and sweep up the pieces. And think of all the misery left behind that will just generate the next wave of radical Islam for the world to deal with.

Nice idea Fantasma, it just isn't a real world solution.