Well, until the Blockbuster Era started with Jaws, almost every sequel was a cash-grab remake of the original. Sequels weren't bigger and better, they were diminishing returns on the originals. You didn't get many Godfather 1&2s or Star Wars OT, you mostly got Friday the 13th 1-9, Herby Goes Bananas, Herby Goes to Panama, Herby Goes to France, etc. We just got WAAAY more original content, because movies were far cheaper and content far less available. If it wasn't in the theater or on the Big Three TV, it wasn't being made, with very few exceptions.
Hollywood has always been a soulless, IP mining machine. They previously were shrewd businessmen, though, who knew how to make money. Now they are either ideologues, who only care about The Message™ or are some arm of a Tech Giant, or both.
Edit: Your statement It's a great and noble dream, that we just let some stories run their course and end. That will require auteurs/IP owners like George Lucas who can A) create good stories again B) have the courage to write a definitive ending for them. I can only think of JK Rowling who has resisted the siren call of money and pressure to not do an "Grown up Harry Potter" series. Helps that she is rich as Canada and fantastically opinionated in the most polarizing ways, somehow.