We can't really see that many frames...but I think the real problem is that we can tell when something's digitally created that it's a bit jerky. We need extra technologies the make the framerate smoother. We don't really need something to be 120 fps, but we do need the game to focus on the key elements, and draw a few more frames there, and use effects to bring the frames together. But, without there being someone that can tell us that a certain game looks better, even at a lower framerate, we have to just pump up the framerate.

But, if you're one of those crazy people that wants a super high framerate, a computer that costs more than your car is the way to go.