Probably because the vast majority of gamers who spend that kind of money on both games and systems want to get as much out of their money as possible, so playing a new game at very low settings just to get good framerate simply doesn't cut the mustard anymore.
Now, for the cheaterstrike rejects who are used to the idea of buying completely new hardware just to drop the resolution to 800x600 and drop all settings to low along with a very high gl_picmip just to get the highest framerate possible as if it matters... well, they don't count.
