moralists judge and preach first, good dramatists witness first. That's why I've not ('til now) been a hugely powerful dramatist whereas even an agenda driven writer such as George Bernard Shaw never allowed his convictions to overpower his stories and characters.
The dramatist is more in the witness position. They may evaluate their characters but they don't judge them. As such they are closer to G-d. By letting go and standing back they make space for more creativity, more life. (It is what plays out on the screen of consciousness....that's why its sometimes called a "screen - play.")
The moralist is in the judgement position. They want to preserve and grow the good, and end or reduce the bad. They have a strong sense of what is good, and what is not. They are intolerant of deviance, and feel a need to preach, analyse, label and sort. They are driven by the notion that they will betray the cause if they open to an alternative point of view. I occupy the moralist position more than the dramatist one.
But deeper still the moralist is really just a drama - just like other roles we occupy such as "superwoman", "lone ranger", "quiet strong type", "poor me", "Mr Angry", "Mrs Nice", "Mr Reliable", "The Rebel", "The conformist" etc. In films like "American Beauty" (the marine colonel who is secretly gay) or stories like Somerset Maugham's "Rain" we see the drama crack, as all dramas must.
Drama's compress change processes that may occur over may years into a few minutes - the moments when new options are glimpsed and perhaps acted upon. So many films begin at points in their characters lives when the characters are ripe for change - whether they know it or not. ( Are feel good endings in synch with life?)