(updated 4/26/12) Have you noticed how many movies are made about fairy tales and comic book heroes? It's quite a list! We've recently seen (or soon will see) films in theaters that tell the stories of:
It just goes to show that Hollywood is very good at mining the riches of popular stories that have already proven themselves in other media. When thinking about what to do for our next projects, there's nothing wrong in thinking like a Hollywood producer and starting from established story lines. The two Snow White movies coming out in 2012, for example, take the standard story and either modernize the characters a bit (Mirror, Mirror), or focus on a part of the original that hasn't been focused on before (Snow White and the Huntsman).
Storytellers have been doing one of two things for centuries: rely on the standard stories, myths, legends and fables of a culture and tell them in a compelling way, particularly using new media; or rely on the standard plot lines in all stories and reshape them with variations of character, setting, outcomes, and surprise. There really aren't that many different kinds of stories in the world, and the variations in character attributes are fairly few as well. Take a simple hero's quest story, though, and tell it using simply a different setting, or a different cast of characters, and you immediately see the potential for variations that can make an old story intriguing in new ways.
If we look at Tangled, we can see that Rapunzel is now a far more interesting character than she is in the standard fairy tale. She has a driving desire (to see the lanterns), and she has a weakness (her isolation). The prince in the standard story becomes a "prince of thieves" in the updated version. The magical element is taken away from the original witch (who now has no apparent powers) and given to the power that transforms Rapunzel's hair. Much of the original story is missing considering it focused first on the parents of Rapunzel and how they offended the witch. Nevertheless, the updated version is in many ways more interesting for modern audiences.