This is nothing new. In the days of John Lennon and Yoko Ono there was political activism in the entertainment arena and these days it's the likes of Sting, Bono, and Chris Martin.
Some argues that celebrities should not become politicians. First of all, they do not realize all problems of a modern policy, because a really good political personality needs a special education. Besides, the policy takes much time, and, as we know, pop stars do not have enough time to overcome political obstacles, because they are busy with their tours, concerts and so on.
On the other hand, pop stars have ascendancy among their fans. Such person can make people listen to him. That is why, nowadays different parties offer to celebrities to join. It increases popularity of the party.
I think it's pretty brave for any music artist to speak out and say something is against the US constitution given the potential backlash against sales it could have in an already struggling industry
In conclusion, pop stars' political activity has its pros and cons. If famous person is a clever and well educated person, he will become a good politician. However, if pop star is a thoughtless person, it can lead to