When they say you own a license of the physical copy, they mean that all the content is owned by another person or company and making a reproduction of that content or making a profit(rentals) without the creator's consent is illegal, not that you don't own the item. That license may be sold(transferred) by you, the current owner, the next owner, and so on.
Digital licenses can't be resold, the company that sold you the digital license isn't required to allow you to download multiple times although most do, and they can pull services for that game at anytime. PSN and XBL aren't going to be around forever. Or if they are around for as long as we're alive, doesn't mean that the content will be available for the older consoles. You can't download any of the DLC that you purchased on the original Xbox anymore and you can't play online. Just wait until that happens to the 360, PS3, etc. It also has in a sense with some games being pulled off XBL and PSN.. You have no security even with GOG, Steam, and other digital markets. If you read their policies on purchasing digital you'd know this.
Digital content can be taken away at anytime and unless we download and create back ups we can't do anything about it.







