I see I'm in a minority of one here, but I still hold that the dancers really couldn't care less what tune is being played, as long as the number of bars is right and the beat comes through good and strong. At least, only a few ceilidh bands I've heard are worth listening to just for the music.

No, to me it's social music, and the purpose is seldom dancing. I can count the number of times I've seen anyone dance in a session on fingers and toes, and the number of times the dancing has been worth it on toes alone.