Re: No sale
Using this offering as a desktop isn't an intended use case. If you're already actively interacting with it, you can just tell ubuntu 'yes' when it bugs you about updates.
The appliance distro's seem to be targeting devices that you generally aren't going to be interacting with at the os level much, so the self updating feature would be a huge plus and aims the counter the usual security issues of IoT things in that they very rarely get patched and updated, even if patches and firmwares exist.
A print server would be a good use case. A desktop environment, not so much since it's going to have a human interacting with he OS all the time.
Also, what you want to do with using Pi's as 'thin clients' is pretty much already easily doable with raspbian, etc.