Maybe due to:
- a fair amount of people who bought PS3s use it mainly as a Blu-Ray player.
- marketing not as good as it was during last generation
Of course, there´s no way for me to know if the former is 100% true, but I do believe it is, at least to an extent.
As for the latter, we all know MS has been far more agressive in marketing, and Sony was a lot better a few years ago.







