I completely agree.
The MacBook Pro Retina 13" is almost the same weight and size as a MacBook Air 13". It no longer makes sense to keep the Air around as a "lighter" alternative.
IMHO, both the Air and the non-retina-Pro are going away. Keeping just the MacBook and the retina-Pro is what makes sense the most (the rest are just cheaper alternatives, and Apple doesn't generally do cheap).