There is a huge usability difference between putting a file in some folder, and having it synced, and automatically syncing all relevant data in an application.

This is easy to underestimate for us technical people, but it is very difficult to explain my mother that she has to put files in, say, Dropbox on her iPod Touch to be able to access it on her iPad. Do something on the iPod Touch, have it available nearly instantly on the iPad in the same application, she understands.