Games tend to go to one extreme or the other. Either people are absurdly tough or die in a few shots to *any* part of the body. The former results in people who can survive being shot in the head two or three times, and the latter results in people dying from being shot in the big toe three or four times. Neither one makes a whole lot of sense.
Fallout 3 is in the former category but nonetheless deserves some credit for its "crippling" system, because that ensures that an injury isn't just some health points but will hinder your performance until you deal with it. Crippled arms = decreased accuracy. Crippled legs = limp around slowly. Crippled head = concussion, blurred vision, tinnitus, decreased perception. Etc.
Incidentally, another game that did that was the first Operation Flashpoint way back in 2001. Shots to the legs would sometimes render the player unable to stand until they could get to a medic for treatment, and shots to the arms would badly affect accuracy.
Another thing OFP did differently to most games in terms of wounding is the way damage is calculated. A hit to any body part would have a certain percentage chance to kill and a certain percentage chance to wound. A hit to the leg might have a 30% chance to kill, for instance, while a hit to the head would have a 95% chance. The remaining 5% of "survivable" headshots is likely to account for things such as bullets glancing off of helmets or taking part of someone's ear off. So the end result is that it'd usually only take one or two 5.56mm bullet impacts to the torso to kill someone, but occasionally it would take three, and rarely even four or five. This also applied to the player so sometimes you would get shot in the torso and die instantly, but on rare occasions you might be full of bullet wounds and shrapnel impacts and keep on going.