Regarded by some as one of the best Justice League story arcs ever written (while loathed by just as many for its sensationalistic elements), Identity Crisis is full of soul-crushingly bleak moments. It's a story that forces the Justice League to examine the proper use of their incredible powers, as well as understand the true depths of evil. The story arc begins when Sue Dibny, the human wife of Elongated Man and longtime friend of the Justice League, is found murdered and burnt in her home. As the story develops, it's revealed that the events of the arc were precipitated by Sue Dibny's earlier sexual assault at the hands of supervillain Dr. Light.
While DC's cinematic universe is a pretty dark place so far, that world is not ready for the violation and murder of an innocent bystander. An R-rating can be the cinematic kiss of death, especially for subject matter that depends on selling action figures. Identity Crisis is an amazing, depressing story, but the world will never be ready to see it acted out on a huge screen, or for Toys 'R' Us to start carrying toys depicting sexual offenders.