Apple doesn't advertise this as the intent, but until the Air I felt that the Phone+Case combo is the complete phone, as it is intended to be used. Add any of Apple's official cases, leather, silicone, whatever, and that's the official "thickness" of the phone. The cameras are recessed, the front display is recessed, the whole phone is wrapped in leather and further customized to your style.

Now the Air has a bump that is so big no case can hide it without also being unreasonably thicc, breaking the trend. I wonder what a case mfg could stuff into the awkward space on the peninsula where the camera is missing so the case provides a uniform surface when laying flat, even if that means a bigger bump on the top when cased. The phone would have a natural angle towards the user, that's kinda nice. Maybe a little bluetooth speaker setup so owners of the Air can more efficiently irritate their fellow passengers.