I did wedding photos for a friend once and went to the house to take some photos but not of the bride getting ready.
One of the bridesmades however wandering in to a room of 5 people with her dress undone and underwear showing and asking someone to zip her up.
I think that a couple of factors come into play. One is the trend for pre wedding 'bride' photos, but also on the morning of weddings, everyone is a little bit hyped up in the brides house and there's usually a few ladies doing things with hair and make up, dashing between room and helping each other and usual inhibitions slide in the atmosphere of the day. Guys seem to become invisible, fortunately