User blog comment:Morganaforever/Episode Review: A Lesson in Vengeance/@comment-5674726-20121118224151/@comment-5674726-20121119145821

And brainwashing would present a more interesting dilemma than enchantment because, while Merlin could lift an enchantment, brainwashing isn't as easy to overcome. It also wouldn't give Morgana a Get Out Of Jail Free card; Morgause might have manipulated her and warped her view of the world but Morgana would still be at least partly responsible for the choices she has made.