I detest the way the piano & spinet & such like instruments sound when playing reels Etc- clever yes, but it just sounds awful to me. An opinion of course...
As an accompanying instrument, it can really add to the effect of a fiddle, flute, box or allied instrument as long as the pianist is not distracting from the main performer. Too many pianists try to demonstrate their skill by finding weird chords and emphasis when not appropriate.
For me, such a piano accompaniment is purely to add rhythm and percussion to a musician actually playing the melody- some pianists even stray into that, such is their self-importance.
   The rule, as ever, is keep it simple- traditional music lovers want to hear the musician, not the accompanist showing off.
   Charlie Lennon, Margie Smith & Violet Tulloch are pianists who understand this!!    too many do not