The whole point of markdown, really it's whole value preposition is that it has nice looking plain text. And don't get me wrong that is a hell of a value to many people, myself included. Yes it is a terrible markup language, And I would encourage anyone doing serious document work to use a language that provides better semantic structure. But I would also argue that all projects that try to add these structures to markdown are missing the point and destroying it by making the plain text ugly.