I partly agree. Such things are usually done just to take advantage of an established franchise, so you get a plot that’s not intended to be expanded + the lack of interest in doing something of relevance because just the number 2 in the end of the title will be enough for it to sell.
But if you could release some universes to the public domain, I’m sure we could have a lot of interesting and novel stuff.
Think of Harry Potter. We have this new play… about Potter’s son and all other usual characters. I mean, why should the Harry Potter universe focus on Harry Potter? We learn there are schools of magic all over the world in I can’t remember which chapter, why should the whole world revolve around England? Can’t Latvia have its own bad guy, can’t Nicaragua its own outstanding magic kid?
Don’t you think there might be interesting stories to be told about all the pirates we never met in Monkey Island? Maybe someone from the time when LeChuck was still alive and terrorizing the whole Caribbeans?