"In war it's probably better to wound your enemy any way, because he becomes a greater liability to the other side." If your enemy is civilized and 200 yards away, this is true. Wound one guy and two guys carry him away. However, in close combat you want to make sure the guy you hit isn't going to shoot at you from the ground, or pull the pin on a grenade and wait for you to get closer. Civilized armies don't send men on suicide missions, but even civilized soldiers are often willing to die to save their buddies. And if the poor b*st*rd is hit hard enough that he figures he will die anyway...

However, now we are often fighting the uncivilized. If your enemy doesn't have hospitals to carry their wounded off to, wounded men will probably be left where they dropped. They'll probably consider themselves dead anyway and just be waiting to take someone with them. They are less crippled by pain than we are, because their pre-war lives contained so much more. You'd better be carrying ammo that kills them, knocks them down, and ensures they lie still.

Look at the history of the ban on dum-dum bullets. It was a surprise cooked up by the Kaiser and the Tsar to embarrass the British and Americans, who had thoroughly learned the need for real stopping power from enemies such as Zulus and Moros.