I would hypothesize that graphics are one of the leading causes for poor PC gaming diversity and why we are seeing a decline of seemingly every type of game except the MMO.

Sure the best PC can blow the best console out of the water visually right now. One could argue that the reason for this is that so much time and money is dedicated to just appearance and that gameplay has suffered because of it.

As for Sony's governing or dumbing down that is pure speculation. An engine can be created with more features then is needed or used. I think that for you to state this is pure speculation especially considering that the cell architecture utilizes more then one core.

It may be true that this new engine can't push the beefiest computers to the limit but I am sure that it would be dumbed down.