While they may derive some fun for the people who have mobility , it feels absolutely disgusting to play against. And while I agree it is necessary for the game, the current amount of it is excessive. Just think about the champs with extremely high mobility.
Around EVERY one of these champs, there is community outcry against them. People hate going against these champs because they are able to unload high damage while being nearly impossible to lock down for other champs. They are able to match other champs in damage and resiliency, but unlike other champions they can spam mobility spells which make them far harder to kill. This very simply makes them better than other champions. This is why people hate going against them. Think about this. When someone picks one of these champs they are having fun, while simultaneously making the game miserable for the 5 people on the opposing team. So please, give these champions some weaknesses and stop adding so many champions who have mobility. This game has more than enough as is.