They should just leave ultimates alone and boost up all other classes accordingly so that everyone would somehow get 20m exp/hour training (I honestly wouldn't mind if TT can do 80k no SE no apple if say a comparable Paladin is allowed to do 130k Blast no SE no apple)...and then up Magician's single target skills for better bossing. 
And if that's still unmanageable with the 200k damage cap, then just up the damage cap. 90k per Ultimate on a mob of 15 vs. 200k per mob attack on a mob of 6 seems more even.
And if that's still unmanageable with the 200k damage cap, then just up the damage cap. 90k per Ultimate on a mob of 15 vs. 200k per mob attack on a mob of 6 seems more even.