Well, you may be right, but what you say is wasted space needs to be there. The bottom has the microphone and the top has the earpiece, light sensors and FF camera. The side to side edges don't have a lot of wasted space. Also, the phone makers make these phone a small as they can. If you look inside of a smartphone, there is no wasted space.
But, like you say, it's probably possible to make a phone with a 4.5in screen that is just millimeters larger than a 4.3 incher. Also, they're making breakthroughs all the time making things smaller. It's high time for a battery breakthrough!
Patiently/impatiently waiting to get my hads on a bionic to see if I like it.