Regarding the penalties causing people to choose suicide: could it be that it happened because no one wanted to limp for an hour to the next objective on those massive maps? I played the release version of RO and thought there were some points where the injuries were a bit too harsh, but I really liked the concept.
Losing a gun when being shot in the hand was ****ing horrible and so was coming to a complete stop when someone shot you in the leg (full sprint to zero, standing there like an idiot). However, a slight, but noticeable penalty for getting shot in a certain area isn't going to detract from the fun, but rather, add to it. I would rather get shot and tough it out than suicide, take a 2 point loss (OMGpersistentstats!!!!11oneleven), and then wait for another wave. In the time I spend waiting to respawn, I could be killing people, and the injuries themselves make the experience better because it feels like I am achieving the impossible.
I even have a way that this could be incorporated without totally ruining the game for the casual crowd. Make some of the injuries % based to help offset some of the rank improvements. Get shot in your left arm -> your level 50 k98 handles like a level 35. Stacking injuries would be even better; you got shot in the hand and the forearm on the same side so you get a 10% penalty instead of 5% or w/e. Then make each wound zone on the body subtract points from a specific category
EX:
right hand = lower reload skill
left forearm/arm = lower ironsight speed
...just add % penalties where applicable and leg wounds should slow running speed or lower stamina enough to make players feel a little weighed down (e.g. injured riflemen would handle similarly to engis or AT).
You could say that low level players aren't going to like the injury feature, but to be honest, the weapons aren't that hard to use to begin with. Weapon sway is already negligible while standing unsupported or after depleting stamina and you are going to give me a ~20% increase in handling when I level up? Come on, this game should be a little more challenging than that. The gameplay needs more depth, and I don't think weapon/character progression alone can provide it.