Well ... let me give a couple of examples, and if the topic takes us too far afield from Tolkien I can split the thread.
Two writers whom I adore: Eudora Welty and Anne D. LeClaire. Welty has Faulker's shrewd eye for the characters that inhabit the rural South. Anne D. LeClaire is the yankee Eudora Welty.
Both have stories that are very dark, but they can also be quite studious in their avoidance of casting shadows onto the future.
So, two stories for which I have great personal fondness, but which do 'soften the edges' in ways that Faulkner would not have done (I think).
"The Wide Net," short story by Welty. A young bride in anguish over perceived abuse by her husband threatens to drown herself in the river, and then disappears. The husband sets up a hue and cry, and townspeople gather to drag the river. But as the story progresses, it's clear that no one thinks the girl has actually drowned. She's hiding to punish her husband. Still, it's an excuse to use the net and pull up some fish to eat, it's an excuse for the kids to tag along and see what strange things are in the river, it's a social event. At the end of the day, the husband finds his wife waiting for him at home, and they both go on as if the incident hadn't happened.
Things that Faulkner probably would not have glossed over: If the husband is innocent, picture a future with a women who threatens to drown herself and makes the whole town go hunting for her when she doesn't get what she wants. Or, if the huband really is abusive, picture having no choice but to go on living with him. What kinds of social constellations create this kind of marriage in the first place? And hold it together?
Leaving Eden, novel by LeClaire. A teenage girl's mother had left her family for several years to go to Hollywood, believing she might become a star after having once been employed as Natalie Wood's double. She returns only when she learns that she is dying of lung cancer. As the book opens, the daughter has found her mother only to lose her again to death. The plot then branches in two directions: (1) obvious to the reader but not to the girl, her mother's best friend (with whom she too shares a close relationship) is courting her father; (2) her mother, she believes, had an illigitimate child while in Hollywood and there is a half-sister out there whom she has never met. She steals several thousand dollars from the mother's best friend in order to go to Hollywood and try to find her half-sister. The father and best friend are frantic looking for her. Bunch of stuff happens, the girl is located in Hollywood and brought home, dead mom's best friend marries father, everything is forgiven.
Question Faulkner would not have glossed over: Wouldn't there be long term trust issues if the girl who is now your stepdaughter had stolen thousands of dollars from you and disappeared, causing untold anguish? Wouldn't there be a feeling of provisional-ness to your forgiveness which no real person could overcome? If your dead mom's best friend became your stepmom, could you really avoid having residual feelings of betrayal?
Bringing this back to Tolkien, one of the longest shadows cast in his story (imo) is the permanent separation of Arwen and Elrond. The movie ignored this completely. Now, I'm not bringing this example to criticize the movie, nor would I accept that this theme was eliminated because of time constraints because lots of other Arwen-Elrond stuff was added. There is an Arwen-Elrond conflict in the movie but it is of a different nature from the one in the book. Specifically, the conflict is resolved by the end of the movie, whereas at the end of the book the conflict has only begun. In the book it is a shadow cast on the future, and not something that can be resolved in the reader's heart except to acknowledge that it would go on and on. This is a choice made by the writer, I think, regarding the feeling with which he/she wants to leave the audience.
I sure don't want everything I read to be a reminder that the world is a dark place and all our futures are clouded by past loss and by the threat of new loss! But when a writer does dare to show those aspects of our vista, and show them accurately and deftly of course, I have a special admiration for that writer. It's not the way to become a best seller! It takes a certain audaciousness ... both with respect to the market and with respect to one's own inner life.