is there any particular reason why you think women cannot be groomsmen in weddings? if i were friends with a man for 10 years, i wouldn't want my job at his wedding to just be passing out programs while acquaintances stood next to him. tradition can be fun, but i think it's time we get rid of gender boundaries once and for all.
No reason I can think of. In fact, I have performed a large number of weddings where there were guys on the bride's side and girls on the groom's. Reverend Frye http://www.serviceministries.org
I thought the movie "Four Weddings and a Funeral" portrayed that option quite nicely with a woman dressed in a tux on the groom's side. Emily Bouchard, MSSW, Life Coach, Speaker, and Trainer
I have done weddings where there were only woman attendees, and funerals where there were all woman pall bearers. I have done many weddings where there were men and women attendees on both sides. If the women are friends/attendees of the groom, they are called groomswomen.