I think the darkness is just a symptom of a bad trend in art / graphics direction. Having a "gritty, realistic" art direction seems to be the popular thing to do, and for some reason the developers see realism as being really fucking dark. I don't get it, I can see just fine in real life, but not as well in games aiming for realism?
People say that graphics have become better over the years, but I'd say that visual appeal is quickly disappearing, which started by turning off all the fucking lights.