The problem with Bobo mightb e that he was a dim character in a sea of new dim characters on MT. If we didn't have Andy and Ramdy and Phil and Spamela taking up all the stupid, Bobo might have worked out better ae THE dim one. He's a rather good character really. The voice and personality are all really good and Bill is a fantastic performer.
The problem is you can either have Bobo or Rowlf, but not both. Bill's Rowlf and Bobo are simoply too close. Personally? I think I might like to have Bobo. Maybe it's because we've been without Rowlf for so long anyway, we might as well keep Bobo.
I do think the muppets could use some refreshing. Maybe retiering certain characters is a good idea after all. I mean, do we really need the Electric Mayhem if they aren't going to use them? Why not introduce an all new band and develope their characters instead of hanging on to the old band that is pretty much out dated? I think that alone would refresh the muppets.
You will always need Fozzie, Kermit, Piggy, Gonzo, and maybe Animal. You don't need the Electric Mayhem anymore, especially when the performers/writers won't commit to the characters.
So instead of throwing out all of the characters, why not just spruce them up a bit?