Come to think of it, why did they go the 'Dream' route instead of the 'Abed got the group to agree to do a movie about the darkest timeline' route?!
Some nice character growth for Jeff that he would make an indulgence like that, especially since Abed's own growth has been about him slowly being better at non-geek interactions with the Group.
Usually on network TV shows 'Character growth' means 'Moving toward the center' and 'Abandoning personal idiosyncracies'. I would hope the Community crew don't see it that way. Having more non-geek interactions with the crew doesn't mean abandoning the geek ones.
I used to be completely antisocial, play a lot of video games and post on Star Trek forums. Now I'm socially active, play a lot of video games and post on Star Trek forums. Real character growth is tangent to the center, not directly toward it.
In my mind Community was canceled after season 3. At least, when I marathon it that's where I stop. The finale of season 3 was the perfect series finale.