It's low power and cheap, and can completely shut off cores when they aren't in use.
Originally Posted by duby229
Plus, games generally don't require that much CPU power. At least, not if they are designed with that in mind. And when they can rely on a powerful GPU with OpenCL (or equivalent) technologies to crank through some of the stuff they may need done. Workloads that the Cell's SPUs could handle will probably run far better on the GPU, and the main programmable core on the Cell CPU was very weak.