Ward Hopping

Why exactly has Riot played favorites with this gameplay component?

It was removed from Katarina during her rework, yet champions like Lee Sin and Jax are still allowed to do it? I'm not complaining and saying Katarina should get it back, but it should at least be consistent, and I honestly don't even understand why it's still a thing in the game to begin with. It's honestly one of the things that makes Lee Sin's kit infuriating and I'm sure his kit is balanced around the concept of ward hopping, but why?