Mean parents, prostitution, and drug use (you forgot the Ep 4 Quinn Tommy heroin scene) are conflicts and plot devices. These elements can and are in any genre. Doctor Detroit was a hilarious comedy with prostitution, abusive parent (Mom), and drug use, and it isn't considered "dark" by any stretch of the imagination. "Dark" is a genre, like "westerns," "action," "romance," "sci-fi," "situation comedy," "drama", or "musical." "Dark" is a mood, an atmosphere, a theme that is grim and borders on the thriller and horror genres. The (rather brilliant) game City of Broken Dreams is a great example of the dark theme. If you want to SEE what the dark genre looks like, play this game, or watch shows like Dark Matter, or Space Above and Beyond, Blade Runner, or Escape From New York for some Dark Sci-Fi, or just about any Tim Burton movie. The Adams Family movies are dark comedies, etc. I'm reasonably sure you would not suggest that BADIK share the genre of these movies. BADIK has more in common with Glee than Blade Runner!
BADIK has not a single shift in theme so far up to Episode 5 and has remained true to its format. It is currently firmly a romantic sex college drama with strong comedic elements, with crime, intrigue, romance, betrayal and other interesting dramatic subplots. But there is yet to be the grim, dread, fear, terror, depressed mood, perpetual darkness, constant rain, and similar elements that make stories dark. These elements emerged (in the form of psycho-horror) in a sudden splash in AL act 3, which had been a romantic/sex drama up till that point. This was intentional on the part of the writer. He was going for shock value and subverting expectations by suddenly derailing the theme to something utterly dark. It was a gamble but in the end, it didn't work. It was sudden, emotionally violent, and painful (as intended). The characters you had come to care about were suddenly made to suffer brutally before your very eyes where moments before you were smiling and enjoying the romantic tension and humor. Shocking changes that, as one player put it "as I was forced to watch." Many people were very put off by that.
Of course there are conflicts going on in BADIK. Conflicts must be present to form a series of words into a story. Something bad happened to Ashley at the AnO party. Something's creepy with Bella. And other conflicts. None of which has to change the entire genre and theme of the story. That is the concern.
If City of Broken Dreams suddenly turned into a light hearted family friendly comedy in the 3rd act, you can be sure, people would be pissed.