Full In-Game Graphics Adjustment

[Betelgeuzah]

They don't utilize the hardware because porting the game over to the weaker consoles with different, and for most genres worse, input devices would become so much more complicated.

Hardware=/=input devices.

PC only games don't utilize the hardware. They look worse than console games most of the time.

Well made PC games still sell very well (look at StarCraft 2, The Witcher 2)

They would sell better as multiplatform.

It's not even about selling "like crap". It's about recouping your investments, and PC audience alone (like PS3 audience or Xbox audience alone) is not large enough for that to happen most of the time.