Aahhmm...Behalf of my Majestic Awesomeness,
I would like to ask a QUESTIONs that bothers me always when thinking about the Purpose of Motor Controller.
I was reading about the Lessons in How to Make a Robot in http://www.robotshop.com/gorobotics/articles/how-to-make-a-robot-lesson-1
then I found out that we need Motor Controller in order to control the Actuators.
Micocontroller and Motor Controller must work together in order to operate a Robot.
[original story: Let's Make Robots]