The way I understand things, Firefly was actually a well received show. I never heard anyone being happy for the cancellation, but I heard many people being sad about it.
My honest opinion is that the show was cancelled more for political reasons. I will present my "findings", although I do not have any confirmed proofs for them.
"Firefly" was absorbed into "Stargate Atlantis" and "Stargate SG-1".
- Morena Baccarin is shared actress (With SG-1);
- Jewel Staite is shared actress (with Atlantis);
- there was a priest-character called "Sheppard" in "Firefly", there was a character called "John Sheppard" in "Stargate Atlanis";
- a lot of the action happens in starships (as opposed to deserts, laboratories);
- the main characters made frequent contact with different civilizations from different planets (instead of being e.g. post-apocaliptic SF, like "Mad Max").
I had the first spark of intuition about this when I recognized Morena Baccarin playing Adria / the Orici. When I recognized Jewel Staite playing dr. Jennifer Keller, I started doing "better research", to easily find the "Sheppard" character in both movies (in the meanwhile I forgot about the "Sheppard" from "Firefly").
All these, many years ago, of course.
If I will remember more, I will add here.
I am aware that they might look just like coincidences taken separately, but taken together, they build up the bigger part of what "Firefly" ever was.