Yea, it's funny, we all like to hate on FOX for "always cancelling so many SciFi shows", but, the reason they cancel so many, is because they give so many a chance
Exactly. Also, people tend to forget that show success or failure is not simply about the whims of executives but primarily about whether ratings and ad revenues are enough to offset the cost of producing a show. SF/fantasy shows generally cost more to make and have smaller niche audiences than mainstream shows, so they're intrinsically less likely to succeed. So they have a high failure rate on every network, even with the best efforts of the network execs to promote and nurture them.
Not to mention that it's been a decade since Firefly
ended and the executives who made the bad decisions about it no longer work for FOX, so it's really past time the fans got over it.