I also have the same requirements
I'd like to create and edit mindmap inside EverNote
Some moments, i considered can i do this thing myself, but i found that it seems the only way is create a application using Evernote's data platform, creating mindmaps outside Evernote.
I don't want this i think, does this method that creating a mindmap outside Evernote has any different with using structured text format to act as mindmap inside Evernote?
I consider it's same, both of two methods are uncomfortable and inconvenient.
So, i persist in suggesting it should be able to create and edit mindmap inside Evernote.
Or, maybe a plugin platform could be opportunity for developers to solve this problem.
I really have a desire to create and edit mindmap inside Evernote.