Would you have preferred Larian just update the Linux version to the (already outdated at the time) release version of the game, thus not getting the updates in the Enhanced Edition?

What make you think there is going to be a huge jump in requirements? On Windows the switch to 64 bit only and DX 11 will have more of an impact. For Linux anyone who can not play the Enhanced Edition would likely, at best, barely have been able to play D:OS. In that case what happens is the same as it is for Windows and Mac: sooner or later people will upgrade their systems and be able to play.