Yet another reason for people to wake up and see how closed and restricted apple is and always will be. I'm actually getting tired of reading about apple screwing people over the same way again and again.
While I hate a lot of the restrictions that Apple places on things, you have to entertain the possibility that the content industries (music,movies,books,etc) heavily push these types of these things when negotiating distribution deals with Apple. As others have mentioned, the things that Apple does control (e.g. Apps) don't have the 'rebuy to redownload' restriction.
but nothing except profits prohibits Apple to stand up for the interests of it's users the way Amazon and Google do, yet Apple seems to always choose it's own short-term interest ahead of it's users' long-term interest.