Muppets Tonight was a show even the writers had trouble with... and once they finally got on track of what they wanted for a series, thing got canceled.
I find Muppets Tonight a flawed masterpiece. There were a lot of strong concepts that somehow didn't gel right. Clifford was made host to make it look like a late night talk show... but with sketches, and more sketches than talk. Some of the skits worked beautifully, but unfortunately, most of those were UK specific skits. There's a lot of GREAT pop culture jokes like Seinfeld Babies and Co-dependance Day... even Kermit's Once in a Life Time cover. But there's stuff that was clunky and didn't work... Deep Dish Nine, Bay of Pigs Watch. Basically anything with the Pigs (except for The Tubbsmith segment... but UK only, again). But when they did those brilliant second season episodes that took characters out of the theater and gave them deeper storylines like when Beaker left for the Star Trek Cruise and Bunsen was just a miserable wretch (try and tell me they're not more than lab partners after that), and the series finale, Johnny leaves Home... that stuff, I hate to admit, was a lot deeper than what they could do on the Muppet show. Just for that one little aspect of taking the characters out of the theater.
Too bad ABC basically didn't want it anywhere in the schedule.