Humans spend a large amount of time not paying attention to what they are supposed to be doing. This might not be such a bad thing.
The fact that both of these important brain networks become active together suggests that mind wandering is not useless mental static. Instead, Schooler proposes, mind wandering allows us to work through some important thinking. Our brains process information to reach goals, but some of those goals are immediate while others are distant. Somehow we have evolved a way to switch between handling the here and now and contemplating long-term objectives. It may be no coincidence that most of the thoughts that people have during mind wandering have to do with the future.
This jibes well with the picture of the absentmindedness typical of some brilliant people.