I'm thinking of a use case such as my Mom (who I intend to get an iPad for) where she will use it and love it but never remember to nor have a reason to sync with iTunes.
She can get her books on it, internet, music, apps - why would she ever actually need to sync to iTunes? 'Her' photos will actually be my photos of her grand daughter synced to it via Mobile Me...
So, I see this backup piece as a hole in her user experience.