Right.... with such details as "autoSpaceLikeWord95, footnoteLayoutLikeWW8, lineWrapLikeWord6, ...". Down that path, any competitor must conform to the way Office already does things, with all of the quirks and work arounds that have been built into it over it's lifetime.
That's the wrong way around, and not what I said. Get all the authors of competing office apps in a room to hash out an interchange format, similar to the HTML standards process, with a core grammer that can be used with clearly defined rules to render any document in the same standard way.
Importing a legacy format should involve translating it's quirks into a standard representation. It should not force every document renderer to re-implement each of those quirks in their renderer.