Specialized combatants don't play together very well in D&D.

[Captain_Karzak]

Well, at the risk of ridicule, I'll assert that this an area that the Alternity games system handled well.

Alternity had wound penalties, but these penalties only generate a moderate impact on your ability to get an "ordinary success" on anything you attempted, but a much more detrimental impact on your ability to attain a good success and it FUBAR'd your chance at pulling off an amazing success (a crit).

So things don't turn into a flurry of misses. What does happen is wounded combatants are much, much, less likely to do something horrible like shoot you through the eye. And if you are well enough armored to absorb most of the damage from ordinary grade hits, it could actually be rational to move on to another uninjured opponent who has a much higher chance of shooting off one of your testicles.

Now every system that introduced wound penalties is introducing a "death spiral," which means that combat has a nearly irresistible momentum. The first party to draw blood (and inflict penalties / death) is the going to be the winning party.

Most games have a way to short-circuit the death spiral. In shadowrun 3e you bought a pain editor, in SR-4 you just fail to care, and in Alternity you could invest in the Resist Pain skill which gave you a chance to ignore variable amount of wound penalties depending on your degree of success. So in a variety of systems, if you do get wounded, you tough-guy action hero doesn't automatically have to become a mess of suck and fail.

One other rambling point I'll offer is that Alternity penalties accumulated at a more than linear rate. A 1 step penalty mean a d4 was rolled against you to muck up your original roll. At 2 steps: d6, 3 steps: d8, 4 steps: d12, 5 steps: d20, and additional d20's from there on out.

Cover, positioning, tactics and shit can also impose penalties, all of which stack. So if Rambo is assaulting an entrenched position, he might pull it off, but if he gets winged, the increasing severity of these penalties - especially at the high end - will really make him evaluate whether or not to continue this course of action.

On the other hand, if Rambo was the one fighting from a strong position, wound penalties alone wouldn't be enough to make him lose the fight. So these penalties aren't deterministic. They could greatly aggravate a bad situation, or mildly complicate a good one.