I'm not one for completely dark either, but there are things that should be done to darken dungeons more.
Dank Crypt - Remove massive sunlight streaming down in every room. Make it darker by having a few small cracks streaming barely any light. Make dark vision black/white, allowing for outlines of objects, etc. but no color.
Owlbear Cave - Remove all the tons of light sources. It's a cave. It should be dark. Maybe there's a major light source near the shrine of Selune, but that should be it.
Necromancer Lair - Come on. There's so much light.
I'm not wanting full blown midnight, but I can almost go through the whole game so far without a torch as a human.
