I'm not super popular here...
I think you're all right.
This is the nicest thing a stranger on a forum has ever said to me.
In my experience with Jace, his ult is not what makes him powerful. Yeah, it's game-winning, but it's everything else he does that makes him so good. I put him in the same vein as
Liliana of the Veil. Her ult is powerful, but her other abilities are good even if you never ult her. Being able to essentially fate-steal your opponent every turn, or
brainstorm every turn, is pretty ridiculous.