Barrier penetration is mostly a law enforcement problem. If you're not in that business then it's simply not your world.
The chances of your getting into a situation where you have to start shooting through car doors, windshields, etc., is pretty much zero. Not absolute zero, you know the never say never thing, but mostly your self defense scenario will be at home or on the street, face to face,
mano a mano so to speak.
Missing your target in the street is a serious issue in that kind of a situation. Missing your target in your house is totally different. And that's where I think over penetration is your biggest concern.
Another free opinion..........
YMMV