Again, I reiterate, EULA. It does not matter what the degree of "op"ness is of the donator kits, just the fact that they existed was EULA-breaking.
And, why can't KitPvP go back to how it was before the new update. There could still be the more op kits available, but bought with InGame money, or Gems. I personally think that It would be more fun than dying almost instantly when you walk out.