Can't properly combo from teleport? Son, do you know what Scorpion players would do to be able to link a spear after a meterless teleport? lol
Kenshi doesn't have the viable mixups that Ermac does in close quarters either with the exception of Kenjutsu, where his ability to "chip people down" is also relinquished.
Mystic's problem is that it's just a hands down worse version of MOS, which is already considered a potentially underwhelming variation with a mid hitting combo starting fireball, giving Mystic a generic fireball ain't gonna change any fortunes.
All Mystic needs IMO, as far as a reason to play it, is less negativity on push (somewhere between -13 to -16), and the Mystic version of EX Lift to have a hit of armor. (cause it damn sure doesn't do anything different currently despite being listed as a "Mystic exclusive move")
With that kind of utility, it wouldn't just be about using push, it's that you have it, makes people apprehensive about what's gonna happen next, and opens up to challenge with other things instead.
So as far as Mystic "needing" a fireball, yeah, something ain't adding up here....
But on the other hand, it's legitimately sad to see NRS beating around the bush with the variation, giving it a purpose would be sooo simple...