Why would better battery life be unacceptable to the average user? Granted, I'm not advocating for freakishly thick phones but an extra mm likely wouldn't be all that noticeable. Honestly, iPhones feel too thin for me. The primary reason I have a case on mine is for better comfort and grip.Apple make their phone with batteries that last all day for the average user. If you are a heavy user or live on your phone, you will need to top off the battery during the day. Apple is into keeping things thin and a battery that would last someone who lived on their phone all day, would be unacceptable to the average user.