I don't know about Descent 2--I didn't have it when it was released, only 1--but I know that Descent 1 had a ridiculously easy soundtrack to rip. I've had those songs forever, since we ripped them from the original game and then just kept the files from computer to computer (although not the game, since it didn't work on later computers). Although... I did notice that GOG converted the files from MIDI to MP3, but that's not a lot of work if you have a converter program.
Bowlingotter, do you mean that the original disk for Descent 2 played in a CD player, the way that Majesty did? I always loved games with that feature! If that's the case, then no, there isn't much excuse for not distributing the soundtrack for both games, except maybe license issues.