There is no purpose to removing this; every hero with mobility can get out of it. Every without mobility is supposed to be countered by it. Or did you forget?
Doomfist is supposed to be a devastating, combo based hero who was a sitting duck if he used his cooldowns wrong. If you wanted immobile heroes like Ana or Zen or Sym to have a better chance against Doomfist, why not just make him louder? Why not allow the team to react to Doomfist sooner by making him shout as he uses Seismic Slam? Why punish Doomfist for landing his abilities?