http://www.latimes.com/entertainment/news/tv/la-ca-critics-notebook-20110320,0,6562927.story

From "Cougar Town" to "Community" to "The Office," sitcoms must evolve in order to survive.

the problem with traditional 30 min sitcoms in particular is that too many changes later on during the latter seasons kill the show, and thus end up being cancelled because of it.

i have seen this happen with some of my favourite shows- they change the backdrop, they add new characters, take away favourites, add stupid OTT story-lines, characters regress or don't evolve as the series goes on to name.

and thus, they jump the shark.

so therefore, i would argue that sitcom changes aren't necessarily always the right option to take.