Perhaps but then Night Elves would have a racial to see everything clearly at night (as they can in lore) and would be deemed "too OP at Night" in world pvp. Also npcs, especially humanoids should have reduced aggro ranges to match or there's no fun in it.
I PvP and I wouldn't mind this. It sounds like a normal racial. I'd love to fight in dark areas with just some torch light. Sounds epic.