Revisionist nonsense, early this gen only Nintendo had motion control and that sold to mostly those who never bought a games console ever, to call it popular, as in the dominant type of gaming is false ......... it was a fad.
Also I don't remember anyone stating that the 360 was a disaster in its first few years.
Sales have jumped the last few years because the price got cheaper allowing more and more to join in.
Call of Duty 4 launched 2007, very much at the start of this gen .......... this has been the generation where pc online gaming arrived on the home console and exploded, so much so that developers now make a deal of it to state they have a single player component.
The HD twins are successful due to games, technology and the new online, connected community aspect of games ......... Call of Duty displays this beautifully.
Also don't discount the core helping to create the positive buzz around a new console that feeds out into the world.