When the game came out, before the big balance patches, I was pretty 'eh' on the variation system.
But at this point, they've seemingly got it so well balanced that I'd be surprised if we didn't see it in the next MK title. Obviously not every variation is tournament viable, but they've done way better with balancing them and making the variations varied and unique moreso than I initially thought they would've or could've.
The only thing that I KINDA dislike about variation system is that it, atleast for me, seems to make learning matchups more daunting than they otherwise would be.