I have been gaming since 1978. I have found dealing with dark topics in-game have made me more aware of "reality" and what coping mechanisms are best employed to dealwith them. Personally, I would have my kids face a sensitive topic in play and learn ways to cope, rather than get surprised by a real-life slap-in-the-face. Watering down a great lesson/scenario is like mixing a shot of whiskey in a bucket of water. You know it's in there but you cannot taste it and it will not have its desired effect. Perhaps put a warning label on the product and let the GM/Players decide.