Main Idea This, Main Idea That...So What?

Obviously Mr. Aronson has been preaching about main idea and supporting details all this week. Let's face it, he preaches about a lot of things! However, as we all know, he does this because he believes it is important. Why do you think it is important to be an active reader and be able to find the main idea and supporting details in a text? How can it help you?