I do struggle with pianos in "folk" music.

I also know what you mean, although I don't entirely agree. I think it comes from the Cecil Sharp arrangements I was forced to sing to at school, which seem rather over-arranged and "classical". I wasn't interested in folk music at the time, and these didn't help. And of course, before electronic keyboards their lack of portability was a problem, and you couldn't rely on a folk venue having a piano in playable condition.

However the piano did have a role in traditional music, Daisy Bulwer being perhaps the best-known example. There are a number of examples of excellent players amongst revival musicians whose playing enhances the music. Like any instrument, it depends very much on how it's played - not just the musician's technical skill, but also their understanding of the music.