That's because people will eat it up if it has that apple logo on it.
Like I said the other night, Apple's greed on obsoleting aftermarket chargers and such, mandatory bloatware I'll never use, and failing to offer me any meaningful features from one incarnation to the next is why I went Android after my 4S.
Also, I'm thoroughly convinced that Apple could slap "iPhone 7" on the back of leftover stock of original iPhones and people would buy it.
Side note: Is 'obsoletion' a word? It should be.