How does this mechanic work and is it even worth having in the game?
Initially I thought you only lost stamina when you got shot in the legs, however recently I just got shot in the chest once (556A1) and lost all my stamina at 75%. This mechanic doesn't really make much sense to me unless it only applied to getting shot in the leg; and even then surely you should be able to run due to the adrenalin rush.
Perhaps adding a minor movement penalty to a limb after being shot for 10 seconds is a compromise, because as is it just does make sense that shooting center mass causes the legs to instantly stop working.
Edit: People are commenting a lot on getting winded when being shot in the chest, and yes, that would probably stun you somewhat. However being winded doesn't prevent you from running, there are countless videos on youtube that show people hurting themsleves and getting winded and for some people they have the instinct to run away from the pain. And thats just what they do.
I'm not saying that there should be no penalty for being shot in the chest or arm, but as someone who has literally been kicked in the chest by a horse, I can tell you its not that hard to run away winded. Not pleasant, but not impossible.