OK, to say it more clearly, I don’t like random damage. Games aren’t about realism, they are about fun. ET is not a war simulation. A real war is a very bad thing, far from fun, something I wish noone had to take part in. And it’s truely random, like real life. A good game is about not being random, to some degree.
There are of course some situations where certainty is annoying, for example:
- Someone with a Panzerfaust at full health will almost always fire before you can kill him
- I like playing covert ops. Against a good medic, I usually don’t have a chance. But that’s the way it’s supposed to be: Covert Ops aren’t an offensive class. So I’ll live with it and avoid fighting enemy medics 1 on 1.
- …
Anyway, I don’t like random damage. Also, it’s a good thing that a sniper headshot doesn’t kill you. This is the most annoying thing about RtcW (non ET). Spawning at beach and being killed instantly isn’t fun.
Actually, you can measure pain in numbers. For example, you can give people a scale from 0 to 10. 0 is no pain at all, 10 is the most horrible pain they can imagine. If they have pain, they can rate it. That work’s quite good in clinical use. Well, back to topic … 
Some time ago I played action quake. It simulated a shot leg by a slower movement. When your leg is shot, you can bandage it, and it “works” again. I like full motion fire-fights, not bandaging my leg in the middle of a duel. Again, this kind of realism doesn’t add fun to the game.