Well, but doesn't Disney's copyright just apply to Disney's own instance? They can't claim copyright on other adaptations of Rapunzel, just their own and the specific style of character drawings and so on, right?
I believe you're correct. The accusation of hypocrisy is based on the fact that Disney has vigorously lobbied to keep characters like Mickey Mouse out of the public domain, while happily plundering the fairy tales and characters of earlier centuries.
while happily plundering the fairy tales and characters of earlier centuries.
It's even more striking if you consider that those fairy tales and characters are the products of many, many retellings and adaptations throughout history. The Grimm brothers didn't write them; they just wrote down one version of a lot of them. In a real sense, Disney's modern retellings are just the latest iteration on this process.