I suspect music audience and licensing terms perhaps.
That's the only reason I can think of why Sega, or Konami hasn't brought more to the west.
There's not even a way to play these appropriately at home without the cabinet itself, or building/buying a specific controller.
We lost out on so many awesome rhythm games just after the decline of Rock Band + Guitar Hero, they could have made a killing here.
It's real unfortunate. Rhythm gamers really have it rough here.

Zenius reports only two of this machine in the US.