Well, it's not like targeting other body parts (except the eyes, yay blindness) had any use in the old Fallouts.

Of course it did.
Crippling an opponent's leg had serious affect on their ability to move in on you; Melee fighters became human shields that could not attack for a few turns while they tried to limp into range. (Especially those most dangerous melee fighters ~Deathclaws)
A low scoring critical to the head did double damage, but the same score when targeting the leg would do 1? times damage and knock the opponent down.
Crippling an arm stops them from using 2 handed weapons and gives them a penalty for one handed ones, crippling both means they can only do unarmed attacks (:rolleyes:)
Hitting the arms would reduce their ability to hit back. Hitting their groin was also a way to make it personal (something that doesn't exist in FO3).
*Someone shoots my dog, they get hit with a super sledge and usually pass out.
The various targets all had critical damage tables that added to the injury. (these effects include crippling, damage multipliers, instant death, knockdowns, knocked unconscious, stunned (turn loss), blinded, and various stat checks that might add more effects if you fail them).
**In fact I used to knock out opponents with the intention of unloading their guns and stealing their ammo; when they woke up, they wasted time shooting at me, and then had no ammo to reload. Try that in Fallout 3.