Well for starters because it's OPEN gl. If you really want it updated, go for it. It also doesn't help that DX10 just came out, along with the first DX10 graphics card. It will take a while for the new hardware features to be broken down and translated to something other than DX10; bear in mind, DX10 and Nvidia were working with their dicks tied together on this one.
------
"Oh how awful. Did he at least die peacefully? To shreds you say. Well, how's his wife holding up? To shreds you say."
Steam + PSN: PHJF