The lights are on
You realize that New Vegas will have the same graphics as Failout 3, right? Bethseda made Obsidian make the game with the GECK and a very small amount of time. It'll look like a huge Fallout 3 mod, basically.
You can't state these things as facts.
Obsidian is using the GECK, but they do have the capability to refine and improve the graphics if time and resources permit. Keep in mind that New Vegas takes place in a different geographical region that underwent a very different reaction to the Great War than D.C. did. Nevada is a desert region which, if I recall correctly, doesn't receive a direct hit from nukes.
To translate that into graphics, Obsidian will most likely spend a lot of time adding new models and textures (ones that they alone will be responsible for the visual quality of) such as that wheelie robot and of course all that sand, and they do have the capability of refining the graphics of existing models such as Brahmin and humans.
I don't expect New Vegas to be a feast for the eyes, but on the other hand I'm positive it will be notably better than Fallout 3. Bethesda laid the structural groundwork by designing basic combat and social role-playing systems, and for the most part Obsidian will probably be spending their time improving upon this existing structure, in which case graphics are a very available and easy category to improve.
EDIT: "There will be both dumb and intelligent super mutants, including the elite Nightkin."
I had been hoping for this. New Vegas is definitely going to be a worthy addition to Fallout, no doubt about it.