Re: Not even scratching the surface
The only tool that ever attempted to place structure first was Lotus Manuscript
LaTeX does, for some values of "structure" and "first". Try document creation with LyX, for example: start by defining the type of document (document class), optionally populate a template, then add one of the structural elements defined for that document (e.g. front-matter, chapter, abstract, section...). Populate it with content and optionally sub-structure. Create more structures. Repeat.
I've used the Freemind mind-mapping tool to create an outline, then export it as a LaTeX document that I could then open in LyX, giving me all the structure and content from the mind map. Not suitable for all sorts of projects, or for all authors, but it was definitely structure-first workflow.
And, of course, all nice marked-up plain text that is handled well by tools such as Subversion.