Nothing is 'wrong' with Barbershop music - It is just a matter of personal taste.   I can appreciate the hours of practice required to get the harmonies perfect, and the thought and skill that goes into the arranging and choreographing, but I can only enjoy it in limited quantities. I tend to listen soloists more so than harmony groups. I do occasionally attend performances of the local Sweet Adelines because I have a friend who likes to go - and it always strikes me that those participating seem to enjoy it very much, and many audience members are obviously very much into that style of music. As to whether or not it belongs under the umbrella of folk music, well that brings us back to "What is Folk Music" and I don't want to go there!