I think some people over exaggerate things too. We have our top tiers in this game, but then you get the toxic members of the community crying about Zatanna, Deathstroke, Killer Frost, etc. I mean it's okay to complain, we all have our characters we hate, but some people no matter how many times you play them, legit think some characters are broken. That's a huge problem.
Luckily, Injustice isn't left with such broken characters as MK9 had. I think every character except Joker can compete in tournament. that's 1 character in my opinion, that cannot compete, compared to MK9 where a large portion of characters could not be considered tourny viable.
I hope when MK10 comes out, we address things that may seem broken and just take note of them, but try and find ways around it, loopholes, search for other characters that may have dirt, etc.
As soon as some people see something they can't deal with, they cry nerf.
There's a difference between not being able to adapt and something being broken.