Solo4114: I'd bet that the big holdup right now is probably some negotiation relating to distribution rights. Like, I dunno, LucasArts might've negotiated some release agreement with some other company years ago for distributing old discount versions of the DOS CD-ROM versions, and it's not as simple as "Oh, well, just pay us $X more, and we're set." Plus, lawyers have to draft contract amendments, and then get them reviewed by the other side's lawyers, who want changes made, which have to be reviewed by the first side's lawyers, and so on and so forth.
I suspect something similar... I'm guessing it will come to GOG eventually but it's hard to say how long it will take. Fortunately I have a huge backlog of other GOG games to play in the meantime!