One reason it is so important to give your hero a moral as well as a psychological need is that it increases the scope of the character; the character’s actions affect others besides him. This moves the audience in a more powerful way. The other reason you want to give your hero a moral need is that it prevents him from being perfect or being a victim. Both of these are the kiss of death in storytelling. A perfect character doesn’t seem real or believable. When a character has no moral flaws, the opponent, who does, typically dominates the hero, and the story becomes reactive and predictable.
