I agree that for phones N is better than N-1 in terms of what the customer is going to get. The question is regarding value to the customer versus cost... how much more would they pay for the phone? I don't think very much if anything.
Also, phones are not labeled with battery life, and I don't think most consumers read reviews. OTOH, they do listen to the sales guy at the AT&T or Verizon store, and they are most likely to push what they are going to make the most money on.
Alan