Yes, it has always been my assumption that there was more to it than just a lack of interest. That is a shame, but I'll tell you that browsing this forum and looking at the screenshots of good old SMAC really got me excited. (Alpha Centauri was my very first Firaxis title and still my most favorite!)
Perhaps part of its mystique is the fact that it is comfortably frozen in time. The unique gameplay and features haven't been duplicated in any other Civ title. I have often considered moding a clone with CivIV, but would this be any better than the original? I have some doubts.
(BTW, one of the things I've always longed to do was to improve the unit models for SMAC. A few years ago, I made an exhaustive search for the neccessary caviar converted but have found nothing as Animatek and the 3d technology that went into SMAC was purchased by another company (I forget the name) which will no longer release the product. Has anyone made any progress in this? Surely somewhere, someone must have the old Caviar Converter 2.0 program lying around?)