One that touches a "universal truth that goes beyond culture, race, age, or geographic location" (see Syd Field on concept) simply has a broader appeal. Because such movies have the potential to move and change more people, they are more likely to get produced in the first place. It's as simple as that.

This means your movie should aim its appeal at men and women, young and old, at home and abroad, if you want your movie script to sell, and to reach a broad audience. Reading the enduring stories, especially the classics, acquaints you with universal themes and eternal truths, and shows you how to relay them without the audience realizing that's what we're doing.