@ mr-money
Why? I think it will just take time. In due time developing companies will aim higher and improve on their game engines based on what they've learned from previous experiences. I can already see a big jump with regard to Ratchet and Clank Future and the already impressive Resistance: Fall of Man in terms of tapping the PS3's power.
Of course developing a simple game is cheaper than developing a more complex game. In the 80s devs teams often consisted of 4-10 people bringing a game on the market within a half year timespan. Today we see development teams with over 100 people working for years on their projects. There's still room and potential for smaller scale projects on the high end consoles though and they can tap a good deal of PS3 performance, Super Stardust available on the Playstation Network rocks!







