I was born and raised in New York and I find the “minhag” (for lack of a better word) repulsive. The Kallah is kept on the other side of the mechitzah throughout the wedding in a majority of these types of chasunahs and all of a sudden she is put in front of the crowd for all to see and (almost) dance with – gartel notwithstanding. I, too, don’t see how this could be considered tzanuah.
Besides the tircha of holding back the mishpacha and extra hour to 90 minutes, the only ones who seem to enjoy it is the badchan (raking in the cash by the hour) and the musician (the same applies).
I’m sure you realize by now that I’m a Misnaged (and proud of it) but I personally do not remain behind (even for mishpacha) for the “Mitzvah Tanz.” Is it really a “Mitzvah”? Does anyone know the source of such a practice?