Actually it was cancelled for a variety of reasons, including the high budget it demanded, a bad timeslot that went up against stiff competition on NBC and FOX, and frequent pre-emptions by news reports. (I still remember how annoyed I was that half of the Bill Mumy episode was pre-empted by a half-hour of Dan Rather talking about the minor and ultimately harmless heart problem that then-president Bush had been hospitalized for that day. They cut to the news report at the worst possible moment, just after a gun had gone off between two wrestling characters and before we found out which one had been shot. It was pretty easy to guess, of course, but what an aggravating moment to pre-empt the show!)
Pre-empting, be it for news reports or sports events or messing around with timeslots has been the bane of potentially (or actually) good SF/Fantasy/etc tv shows finding an audience since forever.