The PS1 and the PS2 were the weakest consoles of their generations, that fact combined with great marketing, fun games and convincing the public that your technogically inferior but still adequate product is a must have made them the big winners. Nintendo did pretty much exactly the same thing with the Wii while Sony suddenly decided they needed a powerhouse to impress hardcore gamers.
They want the PS4 to be the winner of this generation? The solution is easy, make it 75% as powerful as the Wii U and add a gimmick that nobody truly needs but everybody wants. If it worked for the last three generations, why shouldn't it work again?