Apart from the obvious problems (more pixels = more GPU&#x2F;CPU power needed), the more dense the screen, the less effective is the backlight: With a denser matrix, less light passes through the tinier cells, and you have to crank up raw backlight strength to compensate. And <i>that</i> is absolutely murderous for an outdoor phone that has to have a backlight as bright as possible, so you can read it in the sun.