The reasoning for this is simple – the ability was allowing Jett to take the Controller role over actual Controller characters.
However, Riot Games has dropped a new patch which provides some fixes and improvements while heavily revamping Split, one of the more contentious maps.
As for Jett, her Smoke duration has been reduced from 7 seconds to 4.5 seconds.
The idea is to improve opportunities for attackers while lowering any 50/50 checks.