They won't listen to this suggestion because it doesn't make them any money. If players have slower attack speeds, it means you need more funding to be able to do the boss hence more revenue for Nexon from cubes
UPDATE : As of January 22, 2019, according to the patch notes for tomorrow's patch, Jett still will not be fixed. This makes 50 days after being reported and receiving the skill, still unusable. We now are at an extreme disadvantage in the race to 275 and there is no way this could ever be compensated.