Character motivation matter because it propels the plot.
What makes a fiction rich is through a character's motivation, goals, conflicts, desires, and insight. The characters interest and motivation majorly drive the story. When the reader connects with the character they also connect with the story strongly.
The character-driven story helps in the creation of inner debate and decision-making opportunities. Therefore, story events are driven through the character. Events are secondary as they occur through character's thoughts, growth, and emotion.