It's been proven that the good textures are there, the game doesn't load them because it misjudges your PC's specs and loads the crappiest ones available. It's a game bug combined with some driver problems that are all being fixed, but they should have done more QA. This has probably been posted before, it's been stickied on the Steam forums, but I get the feeling people aren't getting this advice here, so it's worth reposting.
Read this about how to force the proper textures and fix it once and for all:
http://www.geforce.com/News/articles/how-to-unlock-rages-high-resolution-textures-with-a-few-simple-tweaks