Every good story needs a reason to be told

"The process of developing a story is one of discovery," Pete (Doctor, director of the movie `Mosters, Inc.´) says. "However, there´s alway a guiding principle that leads you as you go down the various roads. In Monsters, Inc., all of our very different plots shared a common feeling - the bittersweet goodbye you feel once a probelm" - in this case, Sulley´s quest to return Boo to her own world - "has been solved." -
I took this quote from Ed Catmulls wonderful book Creativity Inc. as it describes so brilliant what every good story needs to have: a reason to be told. No matter what the plot gonna be or how often you change your characters or the end of your story, you always should know - from the start you work on a story - what your "Reason Why", your higher purpose, your believe is, your story should stand for.
There is no one better to explain this "Reason Why" than Simon Sinek in his famous TED Talk about "How great leaders inspire action". He decoded a formula which even helps storytellers to start best with their story. Be defining the Why (storyline), the How (hero´s journey) and the What (plot).