Sadly, because popular PC games are gimped by their focus on the console versions which likely make publishers far more money.
I just want the next generation of consoles to come along, as my 6950 feels underutilized. I'm never going to game on more than one monitor or insane 2560x1600 resolutions...
It's not only the console's fault.
PC games that can run on more modest hardware generate WAY more revenue than games that require upgrades. Just look at Valve and Blizzard as an example.