Excellent! More material to disagree with
Before I do so, let me say I do appreciate that you've spent some time and thought on this topic and to contributing to the community for the good of all, and it's good of you to do so.
Quote: Now, there seems to be this general thought among people that torture, rape, etc make for a dark disturbing atmosphere.
This isn't true.
"The castle was full of horrific torture devices and the wives were raped by the lord when they didn't want to have sex"
That isn't disturbing at all
Now, this is difficult, because you say it isn't disturbing at all. You then proceed to explain how to use environmental storytelling to create an atmosphere that explains what is explained in that sentence.
I think what you've done here is criticize a situation that you have created yourself. To qualify, you present the above sentence as though that is what the player experiences, versus your version of what the player experiences, which is purely environmental. My problem with that is that, no one only presents that story as a sentence, you don't walk into an empty room and get a pop up message saying "The castle was full of horrific torture devices...". But actually, you did think it was horrifying when you were in a castle full of horrific torture devices and you could hear women crying out, so it is horrifying to experience that stuff, just not when you see it written in that sentence.
If that sentence appears at all, it is in the description of the game to explain the kind of thing the player can expect, which is 'bad' in our opinion but not really a problem. No one only gives that sort of sentence as the sole story experience for the player, everyone makes a map where you have the objects, noises, notes etc that suggest what's going on. Everyone uses environmental storytelling, often it may not be done well, or successfully, but they don't ever only write.
I certainly don't disagree that environmental story telling is important, and we would probably agree that it should be used more intensely in CS's than it is. It's just a dislike for the way you present it, the rest of your argument, which makes sense, is based on a criticism, and you often make criticism's of sentences that people haven't said, and situations that don't exist, as a way to sure up your own argument.
You don't need to do that, your argument doesn't need those examples of what not to do in order to make sense, it stands on it's own merits. If you do criticize it should be a criticism of the things people actually do, on the way they present their environment and atmosphere. Alternatively, just write it as advice on how to make environmental storytelling work, what you think makes a good atmosphere, and how you think people should use 'unknowns'. Leave out the bad things people haven't done, and the stupid comments that people haven't made.