Using insights allows the reader to grasp nuances of plot when they are not directly stated and understand characters and their actions.
By induction and deduction a reader can infer some nuances of the plot and what the author's intentions are when they are not stated. The reader can imagine and come to their own conclusions and then check if they are correct or not during the reading.
The reader can also understand characters and their actions through inferences, and discover their psychologic indentity of them, what their motivations are and why they do what they do.
This way, the reader can feel more connected with the story.