The Fraggle Five all had their equal share of exposure, but I do believe a few more Cantus appearances wouldn't have hurt, but the rock must be a big place, so his rare appearances go with him wondering the rock and it only made his few appearances that much more special.
I do wish they would have done more with the secondary characters, such as Lou, Tosh, and Storyteller. There was just so much more they could have done with them, but maybe none of the writers could figure out how to put them into the scripts and still stick to the main focal points of the story.