Guden Oden said:You're not thinking like a dev, you're thinking like a gamer! What speaks against it is time and money and sheer laziness. Why do more work than you have to, especially if only a minority will get to enjoy it.
What if Sony delivers that 3D engine (co-developed with 1st party devs) and the devs just need to create the models and textures? Maybe the 3D engine is stored in the actual harware and updated (internet download or on game disc) from time to time as Sony optimizes the engine? If the basic PS3 hardware is strong enough, so that this general 3D engine still looks better or similar then everything from the competitors, then maybe that could work. Devs could concentrate more on the textures/models and the actual game then trying to get the best gfx out of the hardware.
Just an idea.
Fredi