What do you guys think a prototype is? It's a experimental version. Do you know how many concept cars or prototypes have been tested ( probably by apple ) that did get produced.
Maybe that's your confusion: this was not an experimental prototype. The polish of the design, the finish of the case, even the the stickers on the phone indicated that it was a pre-production test model. That's the last step before final production, and far too late to make major design changes.