Plotting out a novel is in many ways like a game of chess. You move your characters around from place to place, sometimes forward, sometimes backward, sometimes up one square and over two. Sometimes you dance with the queen, other times you flirt with the knight. You act and react. But there's always a goal. And there should always be motivation behind a movement or else your story is based on random collisions and could just have easily been generated by a computer program.
I just finished reading a middle-grade novel, which will remain nameless. It's a little-known book, twenty years old, translated from another language--and poorly written. Reading it was like reading a bad draft of my own work. Embarrassing, yet enlightening. Motivates me to give my characters better reasons for being where they are and doing what they're doing instead of just "Because I said so!"
I don't say that to my own children; why should I be allowed to say it to my fictional ones?