Another point I don't think has been mention is that initially 360 and PS3 both targetted their system at a very specific market segment - the core gamer. In every respect from pricing, to design to line-up of game both systems were targeting the hardest of the hardcore.
Now both want to broaden out, with MS doing more to accomplish that this generation than Sony but both kinda figured they'd get the profitable core first and then the vast casual market later. Nintendo however has perfectly gone after that vast casual market limiting MS and Sony's ability to grow beyond their core. The fact that 3rd parties are putting all their mass market games on Wii and the core games on HD doesn't help them any either (although some of both appear on the other consoles).
The PS3 is not the PS2 of last generation, it's the xbox. The most expensive, most powerful and least diversity of games. 360 is better but Wii has an incredible diversity of games for people of all tastes. It is lacking in core twitch action games though so it's not quite the PS2 in that respect but it's broaden the market even more than the PS2 did.







