(Based off a couple of MCU scenes that center around Steve and Bucky lol)
Dr. Starline had a lot of potential beyond what was given to him in his run, as do most "deceased" villains. Hypnosis especially could offer some wild, high-risk storylines. I also just really want to see Sonic become a little unhinged when his friends' lives are toyed with.
Honestly so much of Starline's actions and failures are explained when you realize he does not understand people.
He does not understand why people do what they do, how they find fulfilment in what they do, their motivations, why they think differently from him, that they know their limitations, what drives them to keep going, when they're better than him.
And he probably doesn't know these things about himself.
He was never going to be able to control Surge and Kit