On the other hand, if a game's graphics can pull you into the world to a large enough extent, in other words, if the game is immersive enough so that you feel like you ARE the character you're pushing through that world, I think that can be a great boon to roleplaying as well. You end up using your senses more -- did I just see something beyond that tree? What was that sound behind me? And looking through the character's eyes, you feel "I -AM- this character," as opposed to "I am some omniscient presence dictacting my character's actions through an abstract world that I pretend is realistic."
As long as the experience is compelling, challenging and fun, I think that's pretty cool, too. I love reading, and I also love going to the movies. I love playing pen & paper RPGs, and I also love video games. I don't think that the experience is diminished -- it's simply a different experience that uses different parts of your mind. And both are cool.