Because people like arbritary labels. It really doesn't matter, because these labels didn't exist not too long ago. A real "gamer" just plays whatever is good and fun, if it's GTA or an obscure "kiddie" DS game featuring really cool gameplay.
If anything, I consider the really popular games, most of which made to just be run through w/ minimal trouble,"casual": Halo, CoD4, GTA. These games are made to appeal to the widest group of videogame players possible. That's not "hardcore".







