Firstly it makes no sense for a backlight to be anything but a warm colour at night because it strains your eyes exactly when they are most prone to it (at night, in the dark).
And secondly because it allows us some modest power savings. The chemistry used in our red LEDs (AlGaInP) is more power efficient than that used in other colours. Being a very thin device, we have a small battery, and therefore need to save power wherever we can.
Firstly it makes no sense for a backlight to be anything but a warm colour at night because it strains your eyes exactly when they are most prone to it (at night, in the dark).
And secondly because it allows us some modest power savings. The chemistry used in our red LEDs (AlGaInP) is more power efficient than that used in other colours. Being a very thin device, we have a small battery, and therefore need to save power wherever we can.