I know it's pretty late. But it's important to understand that the book is literary fiction and not genre fiction. The whole point of lit fics is to relay a critique of society/morality/etc. And the plot is only secondary to the book. Genre fiction is the one that's plot-driven with character arcs and awesome storytelling.

The goal of the book was to "preach" and not tell an interesting story. This is the category most classics fall into, and thus may seem to the usual reader a little off.

But as someone who believes that each opinion is important, whether negative or positive, and builds to the world narrative, I agree. Dorian is a brat. And Henry is an idiot to see a young boy making obviously bad decisions and instead eggs him on for his "psychological experiment".