I think that there's more than one reason.
When I went to school in England yonks ago, English folk songs and dances were taught in schools, often by teachers with little or no real knowledge of either. Most of my classmates hated both.
In only one school that I went to, were we fortunate to have a music teacher who loved singing. All the others made singing a chore.
For many years The English Folk Dance and Song Society was run by a crowd of pompous old fogeys who tainted the atmosphere with their bossiness and pedantry.

And then Rock and Roll came along which almost completely absorbed the public's interest in Music and dancing.