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).
Amazon's strategy with AWS seems to be to hype it so much that anybody who isn't using it feels like they are some sort of neanderthal since everyone talks about how everything is moving "to the cloud".
Interesting that he uses Excel as an example since I imagine (I haven't used Excel for a while) that saving data in a modern version of Excel makes it incompatible with anything else (at least it would do if OpenOffice didn't reverse engineer the format).