Although a PC is proprietary free, it's still a very expensive solution to a console in terms of "pure gaming".. from a console, although the graphics will eventually really suck, they are not bad the day they are released (usually).. from a pc standpoint, you'd have to keep upgrading, and that's when they leave the consoles in the dust, but having to keep on upgrading, and keeping it in shape and maintaining, not many people want that.
So the majority of people prefer buying a console, which they can have fun on, without any headache.. true they don't know what they're missing, but that's the story..
I just hope that Valve can do something different, like an upgradeable, and still be cost effective console (or whatever it is they are doing)