Actually in some self-defense classes, the recommendation has been not to shoot for center of mass, but to shoot for the pelvis if they are not armed with a firearm. Destroying the pelvic bone will mean you can safely walk away and they can't follow. It is also a big target area with lots of arteries, veins and nerves.
...plus they have a lot more trouble squatting?
That recommendation is due to the prevalence of criminals wearing body armor. It also reduces the risk of injuring innocents with friendly fire from a through-and-through by not firing horizontally.