People are still surprised that people write software that runs on Windows, really?
Most new applications live in the browser (even MS Office and Intuit Quickbooks) or on your smartphone/tablet.
What about the databases?
Office 2013 is very much a Windows Desktop program. And now a Windows RT App, too.
http://en.wikipedia.org/wiki/Microsoft_Office_365#Office_app...
The fact that some plans include the full desktop apps makes me think the web app versions are not intended as full featured replacements. Or at least are not that capable today.