Whether or not music is a good medium for spreading a message and whether or not that is an efficient goal to pursue, I for one enjoy listening to music and would be happy if there were songs like this in existence and if they were accessible to me. That amount of utility seems worth going after.

It seems likely to me that there will be positive externalities of the type you dispute, but in my mind that's orthogonal to the goal of creating art which allows this community as it exists to confirm and exult in its identity.