Riot should try an experiment with slows.
Lower slow strength on mobile champions' abilities.
Increase slow duration on immobile champions' abilities.
Lower slow strength on mobile champions' abilities.
Increase slow duration on immobile champions' abilities.
The point being?
Lessen the disparity between mobile and immobile champs that's made extremely prevalent by the overabundance of significant slows in the game?
Seems pretty obvious to me.