If every book is about the misery of the human condition... the genre will get old very quickly.
In other words I don't think anyone is arguing for the extremes on either side (total elimination). As an example, I am fine with and even expect slavery, torture, abuse and more to be part of and more often than not even the focus in the Kult rpg. Kult is clearly called out as for mature readers. On the other hand I don't expect that in a game marketed for 12/13+ year old kids, say something like D&D or Pathfinder. In other words, who you are marketing too, IMO has a large effect on what I feel should or shouldn't be explored or focused on.