Exactly this. A bulletproof vest will stop the bullet from killing you, but you are also very likely to receive broken ribs, bruises, and other mild organ damag

Exactly this. A bulletproof vest will stop the bullet from killing you, but you are also very likely to receive broken ribs, bruises, and other mild organ damage. The point is that it stops the bullet. You do not discard the vest because it does not protect you from harm entirely - you wear what you can to keep the bullet from killing you. Possible side effects? Reduced mobility, and if you're untrained, extra weight that slows you down. Is it worth it? Is dying worth the possible side effects? Not always, no, but almost certainly always, yes. That's the point.