@ De85
If taking VGChartz data in this regard I think this chart is far more relevant:
http://vgchartz.com/hwlaunch.php?cons1=XB®1=All&cons2=PS3®2=All&cons3=X360®3=All&weeks=156
This is quite obvious, but as consoles are available for a longer period of time the games library grows (appealing to more different people) and there has been more time to develop top notch projects (which obviously take time to develop, often many years).
And as time goes on consoles tend to receive price cuts (and budget priced games), again resulting into the console appealling to more people (IMO especially wider demographics, such as targeting younger audiences). It's a minor issue that the PS3 didn't receive an official cut on entry pricing for nearly 2 years now, yet the console performs reasonably even at this point. For the long run, I think this probably won't matter much (like we will likely see a slimline PS3 this year).







