It was months before I ever saw daytime in Wow. When I first happened to log on during the day, I was stunned, and even now if I play and it's daytime, it's like a whole other world. I kinda like the real time clock in the game, it somehow makes the game feel more real and persistent.
That being said, darker nights looks cool, but lighter nights plays better. A lot of monitors lose a ton of visibility with darks too, some are just tuned too dark, or are at the wrong angle, or are in a very bright or glare-filled room, it's a tough thing to expect everyone to have set up right.
IMO, give us a night darkness slider (or script variable if you don't want to add more UI). Or maybe there's already a gamma setting that would help somewhat.
Also, if they're going to do this, do it all way, give us torches, let our mounts breathe fire, let engineering/night vision goggles work, elves and dwarves get infravision, etc