I think it would be fun if especially D-Class would instead of always running around with guns also ran around with let’s say axes, knives or pipes as melee weapons. It would also create an more unique enemy that is kind of like 3199, instead of rushing they try to be more careful instead.
Also when I mentioned fist fights in close quarters I don’t mean it should be like an action movie. I mean that if you get close enough to a guard or d class, instead of them just trying to shoot you, they could instead try to push you to the ground or away. They have a system like that in many games like Far Cry, it would make it feel more real.