This is where that one Henry Ford quote about the faster horse is relevant. You don't base an entire theme park off a popular IP.
Star Wars is popular. Harry Potter is popular. But they're not universally popular. By creating fully fledged IP parks, you create a high demand from medium-to-hardcore fans, sure, but you also risk alienating people who "aren't big fans of Star Wars", like, well, the rest of my family. Parks like Magic Kingdom are the most popular in the world because they're approachable. Anyone from any culture can enjoy MK. But Star Wars is such a heavily American property; do you really think the many Chinese and Brazilian tourists are really falling over in excitement to visit Galaxy's Edge or a Star Wars park? No.
I love the Wizarding World lands, but I think the longevity of the lands hasn't been questioned at all by many. Harry Potter is still an incredibly popular IP, don't get me wrong, but it's for all intents and purposes over. There is no Pottermania anymore; Rowling's fans are turning against her, and series like Fantastic Beasts pale to replicate the popularity of the original series. In 15 years, parents who weren't even alive during the premiere of Deathly Hallows Part 2 will be taking their kids to Universal and WDW. I don't doubt that the lands will still be cool, but they'll be dated by 2035.
The lame idea of Tatooine would face the same problem. The original Star Wars is about 40 years old and not getting any younger. It's very likely that most kids nowadays don't care about Luke, Han, and Leia. Batuu is a good (not great) approach because it's flexible. It's involved with the sequel trilogy right now, but it'll take a small amount of effort to change that if need be.