Dropbox already has a very powerful ability to share files and folders among users.
Wouldn't it be great if Dropbox extended that ability to apps?
For example, I'd like to give access to one of my folders to a file-serving app, one of the many that we learned about when I posted a query about it yesterday.
Having app-based permissions opens up a whole new kind of utility for Dropbox, a component designed to enhance applications.