Well in this case it is the other way around, its that people who have
already bought into the device are given this special "privilege" which perhaps makes them feel special.
I think out of the set of possible Internet users, you can differentiate somewhat a group who reads their news on an iDevice. So Apple achieves a certain demographic, and they cater to them with a more curated news experience. Banking on the idea that the people involved will prefer it over the existing channel. Presumably they are already a good group to market to, after all they bought an expensive device and consume news on it, so Apple works to parlay that value into an income stream.
The alternative of having some sort of alternate version of Wired if your user-agent says "iDevice" is much more difficult to control/authenticate relative to the advertiser's expected market.
The next step would be to add blocking vs money as an option. Lets say you buy 1500 "Apple Points" and for 5 points you can "block" (in the sense of it is completely not there) an Ad from your Media. Now when a page comes up and your AdBlocker fires, it consumes 5 points. Perhaps Apple gives 2 points to the media provider to compensate them for not having an ad shown, and keeps 3 pts for itself. Once the user runs out of points and ads start reappearing they can buy more in the Apple Store.
What this does is allows people to convert over from paying with Ad clicks to paying with Apple pts. If you make the conversion rate of Apple Points to dollars fungible, then you can tune the experience to get the most value for the publisher and thus insure them of an income stream, even if all their readers/viewers/players block all of the ads. That then would become the base line value (based on user views) for a property. Robots of course would not have Apple pts and so could be more easily distinguished.
Its a clever plan, I don't know if they can pull it off but something to watch. The current Ad / AdBlocker nonsense is going to reach crisis level here pretty quickly.