The appeal to me seemed more so geared towards online fighting, which I've never done much of. So to me it was useless since your KaF had no story (no bio and no ending...actually I don't think anybody in Armageddon had bio's on disk and the endings were the worst ever for an MK game. So really there was virtually no difference here at all). I can see the appeal and I wouldn't complain if they brought it back, with one caveat: What ELSE could they have used that time and effort to improve? For Armageddon's sake, perhaps they could have fixed the bug with Moloch's name not displaying in his health bar (I think that was him? Or Onaga, or both of them?). Or, they could have possibly spent all of the time modeling and coding that feature trying to get a 3D centaur version of Motaro working.
At the end of the day, its a cool feature for those that enjoy it, but to me the time spent implementing it seems like it could be spent making other cooler, more MK relevant features for an MK game.