I'm still trying to figure out just when it was that "The President's wife" became a political figure.
Is it when the US State Department has her be an official representative for the country at an international event? That would be my first guess if I had zero knowledge of her political activities before this speech.
Michelle Obama is clealy a political figure. The fact that the only reason she got the job as a political figure is because she managed to hook up with a guy who went on to become President doesn't mean that she doesn't have a public political role to play.