the list items being grayed out more for nested items seems specific to the TinyMCE editor
It doesn't happen in the markdown editor, and the grayed out effect also seems more subtle in the markdown editor:
Markdown editor:
TinyMCE:
If I had to choose I'd probably say don't gray them out, but if the TinyMCE effect was more like the markdown editor I suspect people may not complain
EDIT: The markdown viewer also has the more severe grayed out effect, but doesn't have the nesting problem:
