^ This.
If the lore from game to game is going to be contiguous, then they need a definitive ending. It's really the only way to keep the world flowing smoothly.
But... there is no need for the world to keep flowing smoothly... there are ways to "undo" some PC actions... such as with a timeskip: The PC's actions lead to an era of prosperity for some time, and then it goes back to the status quo.
Game-play experience > Inter-game continuity. Let the devs resolve any inconsistencies that arise when they want to make a sequel... Apparently, despite
Daggerfall's extremely open-ended storyline, it's sequel is "The Greatest Elder Scrolls Game of All Time"
After all, was or wasn't the Imperial City flooded with over a million watermelons at the end of the third Era?