The point is, the show ended on a high note and came back with an exceptionally low one.
The stories say the fans wanted another season, though I really don't understand why they would. Sometimes you just can't continue on a theme, especially when half the cast leaves because they were doing other projects at the time. Considering NBC basically wanted to push Scrubs off the schedule ever since the second year, it was miraculous it lasted as long as it did. But anyway, the show was basically going to end one year, a writer's strike stopped an actual ending, and it miraculously got a last season to tie the loose ends. Best example of something I could think of.
I mean, with Family Guy, the show was cancelled a second time a couple seasons before its prime and the fans wanted more. Ditto for Futurama... though there's a conspiracy as to why it was canned in the first place because they didn't want to separate Matt away from The Simpsons. Plus, it took longer for Futurama to really make a come back. Now, with FG, the show over the years lost quality, but it retained popularity through a newer group of fans, but losing a lot of the older ones. But FG managed to be more popular AFTER the comeback.