Origins of Mac OS X's runscript Security Hole
backups cure most ailments.
Image a virus that infects Word documents at a large organization that goes unnoticed for a year because it doesn't actually do anything but replicate itself quietly and subtly, and infects any document it can over the course of the year. Slowly, all the backups of files will be infected as well. It doesn't have to do anything malicious, just prevent a document from being viewed or opened easily.
Every place I have seen Office being used, there are huge volumes of files which everyone can share and update. Boom! Nobody can do anything with the information they have because Office won't work....
errrrm.... wait. I see the flaw in my argument. Office does that all on it's own already.