I've studied copyright laws before, and if I recall correctly, extracting the BGs would not be illegal as long as you didn't attempt to make money off of them (which I'm not). I've been following the game sprite community for long enough to know a few of the basic rules and laws regarding copyright laws...
if ripping the BGs would be impossible, is there a site that has extremely high-quality (1:1, no jpeg compression) screenshots of the various environments?
EDIT: I just realized that AO and AE have been out-of-print for some time (at least, I haven't seen the games in stores for a loooong time), and unless these backgrounds appear in the Oddworld artbook (which right now I'm too poor to buy, I'm spending all my money on college tuition
) it may be the only way some of the 'newer-generation' fans (those who have only played MO, SW) can enjoy these beautiful (IMO) works of art.