Umm, why do people think 2d wouldn't touch 5 percent of the PS3's power?
Imagine any of your favorite 2d games [one of mine is Legend of Oasis]
With high resolution, 1080i display [meaning all sprites, objects, and backgrounds would have to be large resolution]
Full scrolling, animation, and movement effects [meaning all objects move in 24 fps, like real animation, at a high resolution]
2d and 3d high definition effects [smoke, water, fire, ice, wind, etc]
Now add in advanced AI for game play
Tons of event flags
Wrap it up with Dolby Digital or DTS, real multi channel music, surround sound effects, multiple language tracks, etc
Render all cut scenes as fluid HD hand drawn animation
and of course, make it so that everything loads on the fly.
Add in six axis or force feedback depending on the console
That would take quite a bit of the PS3's or 360's power, more than you think.
Think about when your PC loads a 6 megapixel photo...
now have that happen a thousand times on a screen in HD = )