Want to ruin a story? Make it too easy for the protagonist to succeed. Want to make a better story? Play with the idea of making the story world ideal, just, or coddling. If Mother Nature had been a spoiling Grandmother Nature, we’d all be pampered nematodes. So don’t actually write your story without obstacles, just explore it.
What’s the “perfect world”? One where the protagonist isn’t forced to change. I looked through some of the movies in my post Your Story’s Pivotal Scenes 1, to see what well-known movies might teach me.
It may be that everything falls into place according to plan. In Singin’ in the Rain, I made The Jazz Singer a failure, as expected by Hollywood execs. That means Don Lockwood can get away with “show” and never has to become a "real" actor.
Or adversity doesn’t show up. In The Godfather, Don Corleone isn’t shot and Michael slides into a political career without getting his hands dirty. In Ghost, Sam never gets murdered.
Or justice is served. In The Shawshank Redemption, Andy is found innocent of his wife’s murder.
If you take a look at your story and can’t imagine how things might have gone well, it may be that things don’t go badly enough to get the story going. Beware of vague longings that move the protagonist to sacrifice and change.
The world can be a lot less interesting even when things go badly, but not badly enough. In Star Wars, Luke can’t go to the Academy, but he still resists the call to become a Jedi. Until his aunt and uncle are murdered. It’s the final kick in the pants he needs to begin his journey. Consider, with your story, if this sort of one-two punch will be needed. (Note: Flaws may provide a clue. Luke is coming of age, so he has to grow up some for his flaw to lock into place. But one story incident works with Michael because he’s deeply cynical. Similarly, Don is hampered by his craving for dignity, which keeps self-criticism at bay, so a single talkie humiliation resets his life.)
Even “fixing” the story world so the protagonist carries on with a career or dodges adversity or gets justice is likely not to be enough when you explore favorite stories more deeply. Obstacles, ignorance, and villains show up and are clarified in this perfect world. If they don’t stop the hero as surely as the first body blow, they do create problems. So, once you create a perfect world, probe it for its imperfections.
After you do this for the great movies you’ve selected, try the same with your own story. If obstacles, ignorance, and villains don’t show up in sharp relief, you have some work to do. You may find the answers in the newly envisioned classics you’ve been exploring. Or they may be there already, just waiting for you to polish them up so they become visible (and disturbing) to your readers.