I do struggle with pianos in "folk" music.

I know what you mean. I've always had that kind of feeling. However, when I bought some recordings of Jerry Holland, the late great Cape Breton fiddler, the accompaniment on many of the tracks was piano and guitar - and it worked! The fiddle player in our ceilidh band tells me that the use of piano in Cape Breton fiddling is very common.

It's also used to great effect by Phil Cunningham when playing with Aly Bain in the Transatlantic Session. So - like everything else - if done well...

As for piano burning - a doltish, childish thing. If a piano is truly beyond refurbishment, then good re-use of the wood and material is always possible.