HiPhish: Go to the wishlist and look at how many votes are in favour of System Shock 2, versus any other game. By your logic that means that GoG is pissing on System Shock fans as well, not that it's unfeasible at this time. Just because a lot of people whish for something really hard it doesn't mean it is a thing that can be done within a reasonable effort at the time.
Are you saying that the reason we don't get Linux support is because the rights aren't in order (or rather, "not free enough")?
Also, all of the games that are available for Mac right now (except for the Witcher games) runs through DosBOX, ScummVM or has native Linux clients already. DosBOX and ScummVM has binaries for all major Linux distros.
Even if it's too much trouble to make binaries for all different distros, Ubuntu has already been chosen as the mainstream distro, supported by Humble Bundle and Steam. And even then, there's always the possibility of just making cross-platform .sh or .bin binaries.