It is their OS and I'd imagine they can make up a license policy that suits them right. As for myself, I think it is pretty fair; If you break your device X or sell it to someone else you can transfer your license to another identical device X. That's what you paid for, after all. Many companies do not allow one to sell a license to someone else or transfer it to another device at all. Of course some do, but that's it; it is the company that decides what are the licensing options. When I will at some point in the future get another device, of course I will purchase a new SFOS license for it, it's only 50 euros at the moment (and I hope it will not rise too high in the future!)