Before Jyn and Cassian I'd have said a two turn cool down on AoE TM reduction, that's OP. Well Jyn removes all turn meter and gains that much, as well as stunning on a crit with her 2 turn cool down. And Cassian applies ablitly block, defense down, heal immunity, offense down, and speed down (once each) on random enemies with his 2 turn cool down.
So yeah 2 turn cool downs are par for the course with new toons, so re-working his AoE to 2 turns would be balancing more than a buff, lol. I love the idea of him inflicting DoT's with his basic. That would synergize with Vader's zeta upgrade, and makes sense. It implies that his rifle is a flamethrower of sorts, so inflicting DoT's works for it.
As for Stormtrooper I'm waiting for his zeta to come out before asking for a re-work. It'll be on his unique since that's his only ability still at level 7. And having it on a unique rather than an attack or taunt, opens up a lot of potential.