I never understood how you create an application that you ourself would not actually use. It doesn't have to be a one-to-one, but the designers and developers should have experience using similar applications. Case in point is this recent article on The Verge about Apple's iCloud troubles. This part of the article really stuck out for me:
Keynote must work, so Apple keeps a close eye on Document-based syncing functionality. And when it does rely on Core Data, Apple’s software has no more luck than third party developers. Apple’s simple Trailers app uses Core Data to sync, and periodically loses track of user Favorites. "The best Apple technologies are ones they use themselves," one developer told me.
Seems like acquiring Dropbox might be a good plan for Apple.