Well there are differences between these though. The example of Harry Potter:
- People who grew up with Harry Potter now have money, so they can be targeted as an audience
- People who grew up with Harry Potter now might have kids that love theme parks (again, more money)
BTTF and Jaws are significantly older, and to people that are younger than 50 these films were "old" when they first watched it. I am not saying there are no fans of the franchise but most people in the theme parks have no strong attachment to these movies in the same way that Harry Potter fans have.
There is also a second part which is that there is new content released around Harry Potter (TV show, musical, video game) while Jaws (and to a certain degree BTTF besides the musical) don't really have any new media released for decades at this point.
Now what about Monsters, those are old too: Well yes, but a lot of the monsters are very commonly known across different franchises. Dracula, Frankenstein's Monster, Phantom of the Opera and werewolves and mummies are all part of various other movies. They are not "just" in their original movies. Even if you haven't seen the original movies, you know those characters most likely.