For many years - I don't know whether it's still the case as I'm out of the industry now - the major mobile operators in the US had (increasing) requirements ab

For many years - I don't know whether it's still the case as I'm out of the industry now - the major mobile operators in the US had (increasing) requirements about the minimum fraction of the front of the phone that was covered by the screen. They also had requirements for battery life. Given geometry and minimum-practical bezel sizes, both of those factors led toward larger phones.