Costumes have always been with us in the folk song genre. Whether it was Dylan, a middle class kid who donned down-at-the-heels garb as part of his persona or or the middle class boys and girls I used to know in coffee houses in the 1950's who favored work clothing, fatigues, Bolshevik attire, peasant blouses, etc., etc., to show their "solidarity" with the disadvantaged. I suppose if their was not an awareness of "class," none of this would have made any sense - maybe it doesn't make sense anyway.