Sunsets are bad enough. Not everybody has a super bright LCD screen either (I only just recently got one, personally). Night = crap for most folks. Also, it's a fact that most people logged off when night rotated. It's just no fun. Can't see chit, can't shoot chit, can't do chit, basically.
Night = milkrunner's/dweeb's paradise, able to pork the entire map without being shot down by another player. There's little more to it than that, from the practical sense.
Now I admit night is interesting... "once in a while"... But let's leave that "once" to SEA and snapshots and such.