The back button on the iPhone 6 has become unreachable for me. I can't extend my thumb to the top left corner comfortably. Using reachability every time I want to click back isn't an ideal solution. I feel like developers should bring down the back button on their apps similar to how Safari has things setup or at least offer it as an option. Literally one of the most used touch areas of the phone has moved to the hardest to reach part of the screen. Given that the bezel is so big, it would have made sense to make them touch responsive and able to assign them to some sort of hotkey e.g. back.