Hi all! I have read a lot of good opinions on this matter, just highlighting the one that I think of as a fine example of analysis:
Bisso's full post with picture samples.
Also the OP is explaining these things pretty good aswell.
I work as a photographer so i know a thing or two about lighting, color tones and contrast...and i have to tell you, you guys are perfectly right about the matter at hand!!
These things just wont change, it's a given fact how 99% of the people see a picture, how they focus on a given composition, like when the frame of the picture is dark and something's happening in the middle that is lighter...like in Diablo general. Ofc it's darker if its more contrasty and less glowy-unicorny. Ofc most of the horror elements can come from someone's nostalgia, let's not talk about that.
BUT....BUTTTT...the problem roots elsewhere I think.
You almost all concerned about visuals, and forget about the fact that developers are playing and studying other games aswell. They even said it in Blizzcon and some summaries also include a point saying this. Meaning: they have to live up -to some degree- to other games.
There are monsters that need to be hit, even targeted sometimes, loot that needs to be picked up. As a QoL change, in many games they highlighted key elements to be more easy to process for your eyes.
THIS is what's happening that's all. The devs just tuning the game for an average player, and they go straight against the face of what they wanted to do. Horror = contrast. it doesnt matter if it's TOO MUCH LIGHT or TOO DARK, what's important is the ratio. Easy game, no crying children = highlight everything, make it rewarding, progression in an instant.
They have to decide if they want to make a Dark Souls game or Sims 2 withe weapons and demons.
Horror can come from the feeling of desperation aswell. If you don't see what need to be hit in the first 1 second for example.
Imagine if in Alien movie, you could see the monster in 1 second.... peace.