If your story is a road trip, your outline is your GPS.  Not using an outline to plan your story is akin to winging it on a road trip and hoping you don’t end up going off in a ravine.  I used to think that outlines were the antithesis to creativity.  No outline?  No problem.  I wrote and wrote and rewrote with no end in sight.  It was as if I were an aimless hitchhiker, just hoping to go somewhere without a plan for getting there.  If you want to finish your story, outlines are a necessity.  They don’t have to be inflexible.  You can always deviate some if that is where the story takes you.  A GPS will take you on the predictable route, but you don’t always see the great scenery until you ignore that persistent voice that tells you which direction to take.  As long as you know where you are going and how to get there, you can afford to take some detours along the way and discover some fantastic canyons.  Those canyons might be the element that adds color and depth to your story.