There is a quote by Albert Einstein that gets parphrased: God does not throw dice with the universe. I think there's a good writing point there, as well. Part of the fun of gaming is the very unpredictability that comes from dice. Now I tend to put in a range of possible responses before I pick up the dice. In other words, all outcomes from the dice should be possible for that character to react. Dice rolls shouldn't cause someone to act out of character but it can cause them to hit the extremes of what they're capable of.
Writing is just the opposite. There are surprises in writing, especially for discovery writers. Sometimes we find out how a character feels about something only when we get 'in character' and write it. (The subconscious is a wonderful thing. Mine happens to be smarter than I am.) Still, discovery writer or no, I need to know how a character will react to plot events. That's what makes it a story and not an exercise in improvisational theatre.
A heroic character needs to act heroic. That needs to be who they are, their essence. A character needs to be 'Appropriate'. And dissonance, when a character reacts differently from their character, needs to be resolved. It should be a big deal in a story if a soldier is cowardly or a teacher is violent. Now you can change a character by invoking this dissonance and sustaining it. Sometimes that's the point of a story, particularly a short story. But for longer works it tends to make for a better plot, a more satisfying story if the character 'breaks character', suffers for it and comes back to who they are by the end. Redemption of who they are.
Now all of this needs to be deliberate. That, I think, is the importance of outlining. I am so glad I did the 'snowflake method' for Angel Odyssey. I know what decisions have to be made to move the plot forward. The fun and unpredictable part is still there. They 'why' and 'what effect' questions I discovered when I wrote it. Sometimes things don't seem to fit and I have to adjust the character or the plot. But I at least know the story first.
I don't roll dice for it.