This is the most overpowered thing in the game. That very few people realized.
Leg shots slow you down, but you can still return fire.
Arm shots make you unable to shot with 2handed weapons, but only after very hard cripple, most people got high EN anyway, so its not all that easy to get 2nd level of cripple to block the ability to use 2handed weapons from use.
However 1st level of eye cripples, simply makes you unable to hit anything at all. Unless the gun has accurate perk, you are in big troubles because you absolutely must doctor yourself if you want to hit anything. Not to mention most people got 1-5 PE, only snipers are somewhat more resistant to this.
My suggestion, remove the ability from head shots to do eye cripples. In addition to that eye cripple levels should be reworked. You are unable to hit anything with 1st degree of cripple, whats the point of cripple degree levels then ?