Not hard to figure out. Sony is sony's worst enemy. They are pig headed liars (Killzone 2 trailer anyone?). Coming from someone that has experience, the CELL wasn't designed for CPU tasks. While technically it should be easier on developers because you can't write to individual cores (they are controlled by a MASTER SPE), the processors inside the CELL aren't full processors and arent designed for the type of instruction sets that games pose on a CPU. No amount of developers is going to change that. that's hardware.
But on the flip side of that, developers still dont have the time and resources to take advantage of writing for multicore processors either. Most of them are writing for 1 processor and seeing how far that gets them.
As of right now the technology isnt the problem, the brains behind the games are. Not saying they are stupid, but to completely forget or completely rethink how you write a video game is nowhere near easy.