I do it because a lot of courses in my area are short. As I understand it a lot of Pros will still throw a mid on shorter holes still because of the grip and control you get from a mid over a putter. I do it and recommend it mostly for practice purposes. If I were playing in competitions often I would probably go for driving with mids at shorter distances still.
The primary advantage is cleaning up oat, getting good snap, and learning to finesse the disc. That way you have more control when you crank up your armspeed for drivers.