I think most (if not all) tv shows are only going to have so much of a useful life before they run out of ideas and sort of become just an income source.
Sometimes it’s good to die in your prime and leave a beautiful memory, like Marylin, John and James Dean.
I loved how firefly ended - with a wrap up movie, and a very good one.
Yes, when you think about it, a season or two of a good show is really a lot of quality viewing. I was a fan of the show Limitless, which only made it through one season. I think it was at the coin-flip stage as to whether it was renewed. But they had wrapped up the story quite well in the finale. I also liked a cop show called Life, which starred Damian Lewis and Sarah Shahi. It lasted two seasons (one strike-shortened), but all the loose ends were tied up like Firefly. I sort of look at those shows as great mini-series.