What do DirectX 11 video cards cost nowadays? $300-$400? You also need a decent PC with a bit of horsepower plus screen. Oh yeah and you'll need at least Vista.
At the end of the day you'll be spending around $1000 for the privilege of playing this game.
I've abandoned the PC as a gaming platform because I feel it's getting too expensive.
I own an XBox and I can pick up this game and play it without having to bother with new video cards, operating systens, drivers, bla bla.
Yes the Xbox version will not look quite as good. But really, I don't see the difference anymore. 3D Graphics have hit a visual plateau for quite some time now.