Yes it has been a bit of a tradition to use music to bring about political change.
That does not make it good or right.
Any time music is used in this way or any narrowing of the availability of music in public forums- music suffers.
When music is branded as being of a generation, a political point of view, economic class it is cut off from people who are not in that group or do not share the political viewpoint.
When the musical venues, media polarize the music and it becomes branded as on one side of an issue it also stands to loose when the issue or point of view it is branded with falls out of favor. In this case they were on the winning side but in other cases - nationalist germany the music still has not recovered from the stigma of association with a political brand. One should not put music in tat position.
The safer position is to do everything possible, even listening to music that you do not agree with played by people that do not share your views so that open, inclusive public forums for music can be constructed such that the music is branded as an all inclusive community discriminating against no one, a political.
This is not to say that music can not be used by politicos but let it be used at designated political events and not folk festivals unless those festivals present music of a broad inclusive spectrum.
Did the message come before the market place. I think not. The issues were not there when the market for folk music opened up. The market was dependent upon many different dimensions-generational change, nature of past popular music, factors relating to industrialization technology and cities.
The ear was simply ready. Those who had access to the ears with a product that fit could flavor it any way they wanted. The choice could be to present a spectrum of points of view or a narrow manipulative point of view. The ears would hear whatever put into them of a folk nature that made them feel good.
How do you keep music from being branded? You work very very hard to present balance even at the cost of waiting with your point of view until songs of an opposing point of view are produced. There is no real necessity to have political music- lots of other songs to fill the time.
I dont see the manifest destany of political manipulation. It can be eliminated and the music will do much better expanding without it.