Injuries to the hip are breathtakingly painful. A bullet to the hip will shatter bone and immobilize. While not an exact analogy, experienced hunters faced with a charging bear will try to "dismantle" the mobility of the bear before trying to kill it.
When I am carrying a large caliber weapon, it makes sense to shoot to COM. On those occasions, however, when I am forced to carry a mouse-gun, COM shots while eventually lethal, may not have the stopping power as shots to the pelvic girdle. FWIW, I agree completely that if the BG is holding a gun, shots to COM and the CNS are the only ones that make sense.
Perhaps someone with a medical background could offer their insights.
<><Peace