I don't know how anyone could possibly justify buying one of these over an Air. It defies logic.
Processor/RAM are deemed "enough" due to mainly using it for internet browsing at email. Lightest possible weight with a very high quality screen are the only things that matter. Hence, it's the right choice for those people. (I'm typing this on a 2015 13" MBP btw, so it has nothing to do with me preferring the 12" MB).