Sorry XoJ, what you said is mostly false or misleading ...
Most of the real time ray-tracing demos for the PS3 involve multiple PS3s networked together and get worse performance than most single or multi-GPU real time ray-tracers that have been produced since the PS3 was released. Sony did originally play to have 3 Cell processors in the PS3 but they scrapped that when they realized that a (comparatively) cheap off the shelf GPU would provide better performance than 2 Cell processors dedicated to graphics.
Game developers do focus on middleware rather than implement large peices of code, but in most cases the middleware gives you access to the source code allowing you to make huge modifications if you decided to. On top of this, companies like Epic, id and Crytec would port their engines to the cell; and it is likely that Sony would port popular APIs (like OpenGL) to run on the Cell processor in order to make porting easy.
Thirdly, all major game engines are highly optimized code bases that were developed by the most experienced (and some would say best) game programmers in the world. Certainly, it is possible for really good developers to develop a higher performance engine that Epic, id, Crytec or Valve if they were to focus on developing it specifically for the PS3; but you're talking about a 5% to 10% boost in performance at a cost of tens of millions of dollars after you have implemented the engine and all of the tools (like importers and level editors) which are the primary reason people moved over to licenced engines.
