The issue of resolution is about reducing power consumption:

What is the resoluton of the built in display?

The screen resolution will be 720x1440 on a 5.7” screen. (There are more details on our Phone Constraints page.)

Having 720x1440 pixels within a 5.7” screen has the benefits of clear pictures and 2:1 square pixel ratio. Also, higher resolutions would have a higher heat dissipation and increased power usage since more pixels need to be moved around so we are purposefully reducing the heat dissipation and power consumption.