It's not theft, it's what you paid for. You purchase a license to the content, and to stream it as long as it's available, not for eternity. If you want to keep it, at the least download it, and even then you don't have protection forever since it's still only as long as the license server is available.
Not sure this is true. Once the computer is "authorized" for playback, I don't believe it checks a server every time. Case and point, offline viewing. I can download titles into my laptop and watch them on a plane. iTunes has no internet connection while in flight to determine my license rights. The computer is already authorized to view all content associated with that specific Apple ID.