PC graphics are in a very slim way tied to consoles, but really they are tied to dx9. But there are more dx9 graphics cards in computers than their are in consoles.
THe problem is at the moment that while you can add a few fancy features for dx10-11 at the moment, the game really has to work, most of it, in dx9 on older hardware.
This isn't the same case as when DX9 was new, or for a couple years, DX9 was built on DX8, which was built on DX7 and so on. You simply built a dx9 game from the ground up and DX would default to lower settings for older cards.
AT the moment game makers can't just use dx10/11, they aren't built ontop of dx9 with improvements, its a different beast altogether. As very few people overall have dx10 cards, and yes consoles also don't, its a very hard stage for them to just move on and leave dx9 users behind, because its still where a huge percentage of their sales are.
In another year or two, when people buy their new Dell's and get some low end dx10 hardware, then they can look to drop dx9, move forward and stop supporting older features they don't want/need in the engine.
It's really the lack of a seemless move from DX9 to 10, but at some stage it would have to be rebuilt from the ground up to clean out the crap so to speak. Even if we didn't have consoles, the transistion would be a pain in the arse.
But if no one had noticed, games have improved a lot in the past 3 years anyway, maybe not quite as far as you'd hope.
Then again, is it also not a case of diminishing returns.
The difference between a character with a completely flat face and robotic movement, to a pretty detailed face, hdr lighting everywhere, dynamic shaders and high quality textures is insane and obvious. However more and more as we go forwards, the big improvements will start becoming less noticeable, but cost a lot of power. Tesselation in the dx11 demo, well its pretty, but running around in game you wouldn't notice it as a huge and massive difference, yet it still uses quite a bit if power.
