Whats the alternative?
once you start something you have to finish it regardless of whether the war was right or wrong to just pull out now would leave the place in even more chaos than its in now.
Not going to happen I'm afraid. There is no "end" to this that will sort it all out.
From the time of the invasion this outcome, the total fracture of Iraqi civil society and a rapid descent into a rather vicious sectarian civil war, looked a bit inevitable.
Having pictures of what looked for all the world like a lynch mob stringing up Saddam posted all over the net probably hasn't helped either to be honest.
Now it looks like Bush has got his way and the US will continue with the "Stay the course" strategy that you seem to support, despite the increasings misgivings of a lot of his supporters. In fact they seem to be going for a variant of "Stay the course" which you could title "One last push" of pouring in a load more troops and really going for it. But the outcome is going to be the same. Even US military commanders are saying there's no military solution to the mess they've embroilled themselves in.
Sooner or later the US will pull out and let them fight it out amongst themselves. If we're lucky the Shiites wll win quickly and we'll just end up with another fundamentalist Shiite middle eastern state. If we're unlucky the Sunnis will hold out for a fair time, there'll be a protracted civil war, Syria and Iran will get drawn into the fighting and the whole bloody region will be competely destablised.
That's the problem with messing about in the affairs of other nations through means other than the diplomatic. It's bloody difficult to predict all the consequences.
So we support the Shah of Iran in carrying out a military coup to overthrow Irans liberal democratically elected government, because we don't like the idea of them nationalising their oil fields. That provokes a islamist revolution. Oh shit!
So we arm Saddam to fight against the newly fundamentalist Islamist Iran. Oh dear he's a brutal anti-western dictator isn't he. Didn't really think that through!
So we overthrough Saddam and replace him with a democratically elected government which despite all the fiddling we do, looks a bit Shiite fundamentalist. Oh dear that looks like causing a bit of a sectarian civil war. Which might lead to the fundamentalist Iran stepping in to clean up the mess and take control.
Bollocks that wasn't the plan!
You see if you keep swallowing the spider to catch the fly and the bird to catch the spider, sooner or later you have to try to swalow a horse.
It's better not to fuck about with the fly in the first place, but hey ho it's a bit late for that now.