The problem with Fox is that they don't learn their lesson. They had one of the biggest sci-fi shows ever in the X-Files, a show which had relatively minor ratings at first and no one expected to last long. It wasn't until the second and possibly third season that it became a ratings monster. Then, Fox continually put these new sci-fi shows on hoping to duplicate the success of the X-Files but refused to give them the same opportunity. Leaving aside the whole out-of-order, pre-emption and scheduling issues, many of these shows, like Firefly, didn't even get a full FIRST season, let alone a second. Following this logic, the X-Files would have been history almost immediately.
Then, after all of this come 24. Another show that didn't have stellar ratings at first. It was almost cancelled, but FOX decided to keep it. It turned into a phenomenon in many ways. Yet despite this, FOX still continued to cancel shows before giving them equal time. Now some of those shows, even many, may have been bad, but who knows what another season or even a few more episodes could have done? We could easily have had another major breakout show that everyone would have talked about for years. Hell, even TNG had a pretty bad first season.
Oh, and to the poster complaining about how many times the word Firefly appeared in threads: How many of those mentions were of the negative variety from posters who either don't like the show or it's fans? You can't lay those instances at our doorstep.