The military is trained to kill people. The army is intended for use in conventional warfare, when you're supposed to kill as many of the bad guy as possible. There's a good reason why we don't allow the military to be used as a police force in the US and haven't since the civil war.
We've beaten the generals that remained loyal to Saddam, and we invaded the hell out of the place. We won the war, and now we are dealing with the aftermath. The number one thing people in Iraq want is for US troops to leave. Reconstruction ranks second because it's believed US presence is not helping.
Though I also await more information about the shooting of a fleeing minibus that happened to have wounded aboard, I still think this is a good example, regardless of the circumstances, of why we should let our people come home.