In the event of an emergency necessitating passenger evacuation, it is essential that the cabin crew have an immediate and unobstructed view of the safest escape route/s.
Dimmed interior lighting at night allows for much improved visual perception of the outside escape area (looking from dark to light), AND
Having all window blinds up similarly allows for assessment in all directions, day or night.
Standard procedure with every airline that I know of, if not, it should be.