[bcohen5055]

Phone manufacturers typically optimize around a 1 day use case. The battery takes up a significant amount of space and adding more than a day of charge at the expense of a thicker or larger phone typically doesn't play out well in the market.

A perfect example is the correlation between screen sizes and the launch of LTE. At the time if you asked anyone they wouldn't have wanted a larger phone however carriers wanted LTE phones and the market wanted phones that lasted all day. At the time thickness was a fairly standard comparison so what happened? They sold you a bigger screen so that they could fit a larger battery without producing a thicker phone.

[bobajeff]

I had a feeling 5"+ phones sizes had to do with carriers wanting to sell you more data.

(Though I'd guessed it had to do with promoting movie streaming.)