The format didn't need to be reversed, it's (almost) open. Additionally there are plugins for the older versions of Office to let them work with the newer forma

The format didn't need to be reversed, it's (almost) open. Additionally there are plugins for the older versions of Office to let them work with the newer format, and it's much much easier to write tools to do things with Word files now - just crack one open and take a look (it's a .zip file full of XML files).