That's what the Wii version is.
The reason you don't do it is because its too difficult. You can't just upgrade the graphics, its not as easy as that. If you just port the PS2 game you'll never reach the PS3s full potential.
I don't think the PS3 engine sucks. The game sucks but not the Engine it is built upon, if anything the graphcis on the Ps3 look pretty damn good IMO... its how the physics were implemented that sucks... that's not the engines fault (unless it was so poorly designed that it makes working on it a pain). An engine is just a world, how you build stuff in that world is the most important thing.
I would venture as far as saying that its easier to start from scratch on a new system than to port over from the PS2 and try to get equivalent results.
I completely agree with you that the PS2 game is great, and that it has many fantastic features that I would love to see in the NG game... but porting the entire game over is NOT the answer.