I recently went to a festival where the Irish dancers just wore basic black outfits - and found I was able to concentrate on (and enjoy) the actual dancing more, without the distraction of the wigs and fancy costumes. In this particular performance not only were the dancers quite skilled, they were very obviously enjoying themselves. It was a performance, not part of a competition, to an enthusiastic audience, so there was no pressure on anybody to win.   Come to think of it, if it is a contest as to who is the best dancer, wouldn't it be better for everyone to wear the same outfit, so that the only way to grab the judges attention would be the dancing itself? Oh well, to each his own.