There are too many champions in the game.
There are currently 131 champions in the game. Only less than 50 are playable (this number is much smaller for competitive play). How can you expect to balance 131 champions when your changes make only a portion of those champions viable? Seems like a bad decision in hindsight because thats alot more work for the game devs and also, the champion design isn't that unique. If two champions perform the same goal , obviously players will pick the stronger champion. That means your champions are not unique enough to encourage picking a certain champion into certain comps/situations. If you guys don't do something about this, we will continue to see this vicious cycle of only a small portion of the champions being played with each new release and game devs will have to continuously rework champions to "fit the gameplay" which is awful because its easy to fall into that pit of "well, the meta favors this playstyle. We'll just load his/her kit with CC/hyperscaling." leading into champions losing their core, unique identities and having more generic kits.