Those type of shows are so hard to pull off and most are just a catchpharse. Look at Little Britian and Catherine Tate show just to name 2. It is the type of comedy that has died a death. Yet the stations are still trying to push it to the moon and back again. In Extras Ricky Gervais took the piss out of these type of shows with the people wearing t-shirts with catchpharses on them. From Fry and Laurie to Hale and Pace to the utter garbage of Horne and Corden the lists of the shit by far out number the hits like the 2 Ronnies now that was quailty.
So when Mitchell and Webb do shows like Peep Show and it is a great show they get the plaudits for the show and rightly so for the acting. The writers on the other hand have written some top class comedy to be proud of.