For me, part of the tradition -- both the older original tradition and the more modern revivals -- is that normal people play music. They have, as far as I can tell, always done so using whatever instruments are available. If a piano is what's available, you play the piano. If a guitar is easy to come by, you play the guitar. It is hard for me, as a musician, to draw distinctions between traditional music from 150 years ago and traditional music from 20 years ago. I've never considered myself a revivalist, in that I have no interest in reviving anything -- I just play the music I love in whatever way seems good to me. It's easier for me to think of attempts to recreate music from the past as historical, rather than traditional, music making. As such, it becomes to some degree an academic activity, which takes it outside the concept of normal people playing music on whatever instruments come to hand.

Besides, if we're talking about the piano as accompaniment for dance tunes, the piano works really, really well. Nice strong bass, with a full range of harmonic possibilities. For listening, I greatly prefer the guitar. For dancing (which is what dance music is all about, after all), the piano is highly functional, most communities have one somewhere, and lots of people know how to play it well enough to accompany dancing. Why wouldn't they use it to accompany dance tunes? When I'm dancing, I don't really care what instruments are being used -- that's not what dancing is about for me, and certainly isn't what I'm paying attention to while I'm dancing.

I am less sure about arranged accompaniments for traditional songs, a la Britten or Sharp. The music is often very good, and there's no doubt that the melodies remain traditional melodies no matter what is done to them, but the process doesn't strike me as particularly fitting into my "normal people playing music" test.