I don’t think you understand how risky playing melee heroes are. They all have CC but get melted by stuns themselves.
Getting to escape a stun once per ultimate is nowhere on the level of what other heroes do.
Do you think a doom that wastes valuable time going on a long flank to reach the defenders high ground should have all that effort taken away because a brain dead stun interrupted his ability cycle? An interrupt would be once every two fights at least.
In that same amount of time Hanzo just spams logs at the safety of choke and has a better chance of creating an opening pick. Whereas the Doomfist either feeds or trades at best.