Like other clever, well constructed series before it, the meta sitcom wasn't built for the long haul
Here's an unpopular opinion: NBC was right to suspend Community.
Let me clarify: Community is a brilliant show. It's brought something arresting and interesting to a primetime reliant on old tropes done new ways. It gave us a couple incredible characters and afforded for some hilarious episodes.
But how long was it going to really go on for? It had a great two and a half seasons, and it could probably manage another one, but two? Would we need a bunch of weird excuses for why the characters never leave school after graduation, parodying other sitcoms that do the same thing, while at the same time... doing the same thing? At what point would we have started to say, "Wow, why didn't they just cancel Community before all those weird cousins moved in?"
Community was never built for the long haul. It may have borrowed its structure from the standard American sitcom, but it's a different kind of show, one that values style and intellectual content over characters and emotional content. It spends a lot of time being everything else, but less time establishing what it is—you can only parody for so long. That doesn't make it a failure. Community succeeded, just at a different goal.
Some shows are built to last: I've recently become obsessed with Cheers, and the kind of familiarity and warmth that the show is built on was enough to keep it together for 11, slowly shifting seasons. It worked for Cheers, but it doesn't for other shows. We call it a tragedy if a show doesn't keep getting renewed until it's not funny anymore, but sometimes a show can shine within a smaller timeframe. Modern shows find themselves being compared to movies, but they're expected to last about 30 times longer.
Arrested Development is the archetypal indie favorite on network television, unfairly ripped from the airwaves by unthinking, uncaring beauracrats who cared naught for true comedy. For only three seasons it told the tale of the bizarre and self-involved Bluth family, their continuing legal struggles and desperate attempts to save their business. It was different than other shows on TV, featuring staggering comedic performances that continue to enthrall hipsters to this day. But what if it were still on the air now? Was that incessant wackiness going to wear thin at some point? The show was built on a constantly changing, continuing plot, and eventually they were going to need to start changing some basic points or else it would've gotten stuck. And then, those faithful who now decry its loss would have started to turn.