I would never argue that escapist entertainment such as videogames should not explore the dark reaches of the human psyche or behavior. Where My Lovely Daughter falls down for me is not the grim subject matter but the somewhat artless narrative and pacing and the repetitive gameplay loop that sustains the experience.
Although there is a lot of repetitiveness, My Lovely Daughter is a different and unique game that will pull on your heartstrings. Just keep in mind though, that this game is designed to upset and to disturb you.