This feature is already used in some FPS games! Even Battlefield 3 which is an arcade FPS had this feature. Later, BF4 removed it but lots of player prefer BF3 gunplay over BF4! BF series actually were going more and more toward arcade style.
The feature Im talking about is when you receive a shot, the bullet impact would make your body shake thus disturbing you aim, e probably causing you to miss your shots if you are shooting or making hard to you keep your cross-hairs steady.
In BF3 when you are running and receive a shot it cause you to slow your speed. That's cool but I think it would be better if the shots just make you shake when you are running causing great difficulty to keep you running direction straight like if you were in earthshake or something like that. I think the impacts could also cause some suppression effect like making you vision a bit blurry or other vision disturbing effect.

This makes the gameplay a bit more realistic and I think most players of this nich like realism!

Anyhow, any effect related to bullets impact on character/player body would be very welcome!