[microtonal]

They get the latest bugfixes, and they don't need to worry about all this downloading installers rubbish that seems so last decade.

They could also distribute Dropbox through the Mac App Store, then they wouldn't have to sneak in SUID binaries and run background processes with launchd. As an added bonus, Dropbox would be sandboxed.

Before someone says it can't be done: the OneDrive app is installed via the Mac App Store, is sandboxed and provides Finder integration. (Yes, the Office badge would probably be a problem, but that is a hack now anyway.)

Edit: that sounded too negative. I agree that this benefits a lot of users, I just wanted to point out that an App Store version would be even better.