I think Michael was pretty much played out
His character suffered mostly because they could not (or maybe would not) allow him to genuinely move on to independent adulthood. To better achieve this, they needed to de-emphasize his relationship with Karen, a character who tended to dominate all their interactions. Obviously they couldn't just dis-own one another, but he needed to be seen doing more things on his own without Karen trying to offer "advice" (smothering him). Though they made an effort by having him work at Sumner Group, they never allowed him to fully cut the apron strings. In order to become more of an independent character they should have de-emphasized his Fairgate roots in favor of his future.
A modern comparison (and well-executed solution) occurred last year on
General Hospital, coincidentally with a character named Michael. He'd also grown up on the show with a domineering, frequently smothering mother named Carly who meant well but refused to see him as an adult even as he married, had children, ran his family company, etc. In the effort to make Michael "his own man," they had him leave town for several months, then returned him with a slightly older recast who didn't physically resemble the previous actor. Most notably, the new actor is rarely if ever seen in scenes with the actress who plays his mother. He's going about his life raising two kids while juggling relations with his unglued ex-wife and his ex-hooker girlfriend. Carly is a non-factor in his stories, and it's no longer a chore to watch him. The "fresh start" has made an incredible difference in the character and how people see him, and the change has even made his mother a bit more palatable (only a tiny bit). She isn't obsessing over her son's love life, his custody battle with the ex, or even trying to break up his romance with the hooker.
It seemed that the then-writers of Knots preferred to write for characters like Paige and Linda rather than Michael or Olivia. But can you imagine the cringey carnage if they had opted to do a Linda-style revamp of the character of Michael?
