I don't even see why you'd need them to work in other parts of the brain. Directly manipulating mood and emotion would already give you an enormous power about a person.

As psychology research shows (skinner etc, the current discussion about manipulation in games) - controlling emotional rewards would also have a big influence on the "rational" decision making of that person.

I think the "let's publish the good-natured stuff" is more about the target values they seem to tune this system for. Sure, you could tune it to counteract mood disorders and steer the subject towards emotional stability. You could also tune it to other targets.