I wonder if, phones could just have a UI area on bottom half and display area on top. I just can't reach the top of the screen anymore with my thumb, and there are lots of controls that visually makes sense to be in the top half.

iPhone was brilliant from cost and mechanical design perspective - there are just so few moving or essential parts in post-iPhone phones. But maybe, just maybe, this solution is not as good as it seemed, maybe it could be better. Just my cynical POV...