Broadway has not enforced a dress code in years. Often when opening night tickets are available to the public, the general audience dresses no differently than they would any other performance. When I attend opening nights, I wear a button-up shirt, slacks, and oxfords (which I wear for ordinary performances as well). It's nice to dress up, but by no means is it required for opening night any more than it's required for ordinary performances. I went to the opening night performance of Spring Awakening this season and was seated next to a man who was wearing cargo shorts and flip flops. The bar has been set incredibly low these days.
"Mostly, I loved the size of these people's emotions. Nobody has emotions this size anymore. Outsized emotions. Operatic emotions. Kushemski and Vanda are like Tristan and Isolde, they're Paolo and Francesca. Nobody's in total thrall like this anymore. Nobody's overcome by passion like this, or goes through this kind of rage." Thomas, Venus in Fur