Meh, I don't thing graphics are really updateble.
The original engine is pretty old. It just doesn't have that sort of stuff.
We don't play Doom2 in HD-graphics either.
Also, updates are free, new games aren't.
You don't earn much money by desperately keeping a game alive (although BF1942 doesn't need desperate people yet, it's still good).
That's why they made BF1943.
By the way, if you want to play BF1942 with some new graphics, you could try installing the free iZ3D driver. It is actually designed for expensive 3D screens that use some sort of polarization, but it works on normal screens too, as the driver also supports those old fashioned red/blue 3D glasses. It's not restricted to special polarization technology. It works as far as I know on almost all 3D games, but I haven't tried it on BF yet.
I don't use it a lot, but I think it makes games like Age of Empires 3 look freaking epic.
You can really see the depth. The normal menus are very high, and the world is very deep. It's awesome.
By the way, I really recommend using it only for games that normally run at at least 60 frames per second.
When activated, this driver will require your pc to render two frames at the same time. I don't think it will just divide your fps by two, as the two frames have different point of views, creating real 3D effects. It might even be slow on games that normally run at 60 fps. By the way, some games have a fps limit. I don't know why, but I remember Call of Duty 4 not being able to get higher than 60 fps. For some reason, this limit stopped working. I was still playing at max quality, but for some reason, my fps went to 150. That gives you some pretty nice averages.
EDIT: I just read that DX10 will be supported when version 2.0 is released. This version isn't out yet, but it's supposed to be in closed beta.
Also, it seems there isn't a x64 driver yet, but the 32 bit version is supposed to work perfectly in x64 systems.