OK...get this seared into your memory; We shoot to stop the threat. NOT TO KILL.
If the bad guy happens too die, because of the wounds inflicted trying to stop his attack/render him no longer a threat, well thats just how it goes. You NEVER MEANT for that to happen, according to the law in many places.
Its all nonsense, in a certain sense, but its very real for you should you be in a situation that LE will examine with a microscope.
At crunch time I dont think we will have the luxury of shooting for an arm or a leg over a center mass shot. Even if you did, if you didnt consider the person a serious threat of death or serious bodily injury, you have no business shooting. And since we have already established that you DID need to fire, you dont mess around with taking shots not designed to stop the threat.
See some videos of people who have taken an unreal amount of SERIOUS hits who still keep shooting, and that will put the issue at rest for you.