IMO, the games take too long, and the board gets "too busy" to appeal to a wide audience. It's also very inelegant that the line of drone takes up so much of the play area. It would serve them well to tweak the UI: maybe have stacked 1-hp units reside on top of each other and merely display a count, rather than splay across the board.
Games taking too long, time-wise, can be addressed by playing with shorter turn timers, but that's obviously much more difficult for inexperienced players.
Re:stacking like units, they can't stack all units of the same name, because they may have differences of status (current hp, stamina, exhaust, etc). Even drones are either clicked or Unclicked. They could have two stacks, I guess, for clicked and Unclicked drones, but then you lose some "at a glance-ability" (which is totally a word).
Unrelatedly, I finally made it to tier X last night, after bouncing around tier IX 90%s for a dozen games. My next to last game left me at IX 100.0%, which was ... disheartening.