I’d love to see block-based editing (drag+drop), and I have some thoughts about how the UX should be handled if indeed that gets added.
But mostly I just wanted to add support for the much simpler and hopefully faster to implement suggestion of allowing nested checkboxes. I find this to be a tremendously useful feature in the other tools that support it. Also allowing some kind of bulk operations on check boxes would be nice (though low priority), e.g. “Check/uncheck all” and/or “Check parent and children” (check all boxes nested underneath another).