Well put! A friend of mine likes to say "faulty memory is the driving force of folk music." By that he means when people try to reproduce the music the way they believe they heard it (melody, rhythm, harmonies, lyrics, etc.), they don't always right. Therefore, the evolutionary changes that the folklorists spend their lives studying were not necessarily conscious. On the other hand, revolutionary changes, such as introducing an entirely new class of instruments, certainly are conscious.