I forgot what our ultimate consensus was on the other thread, but if I recall, the only reason the flappers are up front is because they're (illegitimately) taking the place of an actual liturgical/clerical choir, which used to be up front, in the sanctuary. Even at seminary, I must admit that I didn't care for this at all, although there the flapping was generally hidden from the faithful as we were in a circle formation and the flapper kept his hands low, below the heads of the seminarians. IMO, you do not need a flapper in order to be able to keep time. I played violin in orchestra and sang in the top choir at STAS, and I don't think I ever even looked at the flapper. I was looking at the musical notation. Flappers serve no purpose other than to create a spectacle ... which during the Holy Sacrifice of the Mass reduce to a huge distraction.
They probably brought the flappers back for Holy Week. Are these the post-1955 Holy Week Rites that require more "participation of the faithful"?