I don't think the problem was Colter. He just didn't have anything to do in the series as he was Luke Cage 24/7/365. Like all other superhero joints he needed an alter ego for more storylines and better plots. What's Superman story without Clark Kent or Batman without Bruce Wayne. The writers gave Cage/Colter nothing to work with whatsoever. He had a bar but they destroyed it. Then he had a barbershop but it was closed with no customers. I was like damn give this dude something so he's not just walking up and down 125th or Lenox Ave all day and night like he was doing. Just horrific writing all around imo.