with the previous format being essentially a memory dump, i'd say that's progress
That’s correct - I worked with MS team that documented old formats, and they said that sometimes they don’t have people left who knew what specific struct was intended for - although that was mostly for people PowerPoint and Visio, excel and word was better documented
Actually Excel was the only one that had official, freely available documentation for the old (now legacy) file format.
You don't remember correctly. Word's docx format is far more intelligent than openoffice ODT, despite propaganda to the contrary. With one exception: word's zip files don't have a convenient magic header. The way it works with ODT, and a bunch of other formats is that you put an uncompressed identifier file (`mimetype`) as the first entry inside your zipfile. At byte 30 (of your zipfile) you then get `mimetype$THE_MIMEMETYPE`. This is a nice trick and works for any zip-based format. Sadly, docx does not do that so you have to go by file extension or look at (more of) the contents of the zipfile.