dryuppi
I think the visual/contextual similarities with the original manga/anime run do in fact point more plainly to the reality of the mouses' relationship with their public domain reworks.
That is, what they did exactly exemplifies excellent use of the public domain. They did more than just updated reproductions of the original works. They used the public domain as a starting point, an inspiration, but told their own stories; often wildly different from their source, like, where I mention elsewhere, The Little Mermaid.
The problem focused on should be that while they benefited from having access to these works in the public domain they have spent time and resources to ensure others are unable to do the same with work they have financial control over that should have long been included in the public domain.
The messaging is about curiosity and exploration.
The moral is about accepting when things fail to go as you want, and choosing to avoid harm to others for your own benefit.
There is an anime adaptation that is faithful to the original story.
https://en.m.wikipedia.org/wiki/The_Little_Mermaid
https://en.m.wikipedia.org/wiki/Hans_Christian_Andersen%27s_...
What lessig is likely referring to is the violent and grotesque consequences of the original Grimm stories as well as their brazen antisemitism.
https://www.history.com/news/the-dark-side-of-the-grimm-fair...
Which is a reference to the Lion King, one of the mouse’s 2d classics, which is also one of their most egregious derivative works.