Well, from my experience with the newer IE games and such the meleers move in while he range attackers pick off the the spellcasters. Also in NWN, in the later expansions, enemies use Disarm, Knockdown, and the such on stronger opponents while range attackers focus on dropping the weaker ones.
GTA's focus is on action. Everything in that game is Action based. From driving, to flying, to shooting, and so forth.