Madonna has a long history of standing up for marginalised groups and being very political. She was dropped by Pepsi in the late 80s for 'daring' to represent Jesus using a black actor in the Like a Prayer video
That wasn't a political statement - that was what Madonna is best at, self-promotion and publicity. She knew the black Jesus thing would cause a massive fuss, she enjoyed the controversy, the newspaper coverage, the televidion reports. Her career in the 80s/90s was just one self-promotion stunt after another.
She's struggling now as there is a younger breed of shameless "celebrity" publicity seekers like the Kardashians, Lily Allen, Lady Gaga etc etc etc who are competing for Madge's limelight.