> The problem, of course, is the cost of that inefficiency is external to the vendor.

How so? The impact of power efficiency is arguably as immediate to a mobile phone manufacturer as it gets. These things are battery powered, and many people are struggling to make it through a single day on one charge!

Of course, that's practically exactly what battery size is tuned to – making it through exactly one day for most users. Knowing Apple, they'll just make the next flagship half a millimeter thinner again rather than risking one and a half days of battery life...