Question: Why is this Org mode-specific?

[rswgnu]

It seems like most everything you are doing with this package would be useful and would work with regular Emacs star outlines (aside from special display formatting). Is there a major reason to limit it to Org buffers? You could probably generalize the code and then add a few org-specific commands on top to handle special needs within Org buffers, I would think.

[alphapapa]

Something like that could be done. It would require a significant amount of work. It wouldn't be useful to me, because I don't use outline-mode files. If someone needs a tool like that, it would probably best be handled with a fork. This package is designed very specifically for Org features.