I think a park full of licensed 'lands' is something Universal or Six Flags would do or have already done. It can be fun, but there's not a lot of creativity in doing that.
And you never know how well it will age, 20, 30 years from now. Will people still care about Star Wars (as an example, not specifically Star Wars) enough to want to be surrounded by stuff from those movies? You never know how tastes change after a few decades. There is a burnout factor with anything that specific.
The fact that Disneyland has general titles for the lands means there's a ton of flexibility with what they can build in them and also gives them the flexibility to remove rides without worrying the removal or addition wouldn't conform to something so narrowly focused.