payn
Glory to Marik
Penny Dreadful was interesting like this. The showrunner claimed he was allowed to end the series as he wanted, though seeing how things unfolded that seems very unlikely. I mean they introduced Dr. Jekyll, but we never saw Mr. Hyde even though it was building to it. They introduced a new character just 3 episodes before the end (a female Indiana jones who was kick ass) that served little purpose.I'm not talking about inspiration. I'm talking about opportunity. As in "are you allowed to write an ending at all."
Babylon 5 almost didn't get the chance, and then the networks yank them around so the final season was decidedly lower-caliber. Person of Interest got cancelled, but luckily were given a half-season to manage to wrap things up. Timeless only got a 2-hour TV movie to resolve a major plot point. Firefly just got cut off mid-season, not even airing all the episodes made. ST: Enterprise got cut off just as a guy who actually knew what to do with the show got the reins.
The list goes on for shows that were not allowed to attempt to find a satisfying end.
What seemed more likely is the showrunner expected at least one more season, but didn't get it. The show may have ended like the showrunner wanted, just not when the showrunner wanted it to.