I like to use the story of one of my parents. Big tall guy, never used technology, big fingers and always complained buttons were too small etc etc.

Now the guy loves his big iPad and his iPhone that he wouldn't go any size smaller because he'd struggle to see what's on the screen. The only challenge he has now is he likes the bigger phone, but struggles to keep it in his pockets when working, when you add in a protective cover.

People don't often know what they want, they're just driven by what they've had and whether they think it has worked for them, which most people can justify their own decision.

I do think however, that there will become a point where phones simply are too big. I'm just not sure how far off we are from that.