It adds an immense amount of complexity that is better left for more specialized applications and use cases.

At least for now, kind1 is the common ground everybody has and it should remain that for the foreseeable future, at the basic level it's super easy to get started, easy to read, easy to write, easy to display.

If you start publishing kind1 notes with HTML, Markdown, editing capabilities or kind1 notes that depend on custom interpretation of new tags or requiring fetching or other notes for them to be rendered correctly you're breaking that.