I take that you haven't played the games. The only reason Bethesda included VATS in FO3, is because Fallout 1 & 2 had an interface for selecting targeted shots; where you could ~at linear progressive risk (of missing), try to shoot the eye, groin, head, torso, either leg, or either arm. Hitting them could score additional critical damage, that in some cases knocked out the opponent, or killed them outright.
VATS mimics the aimed shot UI appearance; though not its functionality. The name VATS itself, is a trite backcronym they created because of the "Vats" place name ~a location on the world map in Fallout. It was the Vats of FEV virus.
http://fallout.wikia.com/wiki/Mariposa_Military_Base#Vats_.28Fallout.29
That's the dumbest of the dumb things they added to the series.