It's a (silly) decision by Id not to let PC users muck around the config since from what I've read the engine scales itself automatically to provide 60fps at all times.
This. It's easy to scale for 60fps on consoles due to the lack of hardware variation, but impossible for PC due to the wide variety of graphics cards and screen resolutions.
original res : 1600x900 (nature) flickr res : 1024x576 force Vsync AA 16x
The floor textures in the screenshot with the RC buggy is rather poor for a company of ID's stature. And is it just me or this game has no bump mapping whatsoever?