Er, yes you can. It's strictly a physical constraint. Hardware has limitations. No matter what casing the hardware is housed in, the technology can only do so much. The hardware is 5 years old. The games look 5 years old. It's only now that games on the ps3 are looking as good as PC games COULD THEORETICALLY of looked back then. However there is some leadway for the consoles as the engine is designed specifically to work for one set of hardware. Optimization is way better.
So of course you can make games that look decent for PC specs (like uncharted 2, killzone 2, god of war 3, heavy rain) but the result is that most console games are just incredibly well optimized 5 year old pc tech (unreal 3 engine etc.)
The reality is, consoles have held back PC gaming. Who knows what wonderful things we would of seen by now if this is not the case.
Regardless, the consoles have graphics processors that just simply cannot and are completely incapable of performing some of the lighting and texture work that crysis does. It's leaps and bounds above the consoles best.