As mentioned cartoony graphics age really well, and if done proper, give game a nice aesthetic. Also consider that if wow was photorealistic, how many people would go puke as soon they enter undercity and see abominations with bellies open and guts hanging out? I, for one, am not interested in HD anatomy lesson, also torture racks in scarlet monastery and similar things, wow isn't exactly pacifistic universe, but art style makes it easier to show without inducing nausea.