You want to moralize your story? Great, but be subtle, give both sides of the argument, and make it thought provoking. Let people arrive to their own conclusions, and if one argument is really better than the other, you'll see that your readers or viewers will agree with your line of thought. The fact they arrived to their conclusions by themselves will make it more rewarding for them, and the lesson will stick in their minds for much longer.
It's a good thing that I decided to write reviews. While watching a movie or reading a book with the aim of reviewing it I notice things I would otherwise overlook or forget about. I think about what I like and dislike about the writing style. This helps me improve my own style.