It's the final battle or the final test. By making sure the character is in crisis, the drama has a lot of captivating power. Resolution means all the conflicts are resolved and there are no loose ends. This is a power-point because it will make the viewer tell others to watch the movie. If the film wasn't satisfying, he will tell others to avoid it.
People love happy endings.
Not because we all live with our head in the clouds, but because happy endings tell us there is a solution to our problems. Life is not just endless torture, there is hope, and life is after all, worth living. And we identify with the main characters - we don't want to leave the theater depressed.