I researched a bit. The first thing that came up in my mind was the band "Black Veil Brides"... But of course, the band name is actually the opposite of what we look with the black skull and the white veil.
I believe that the meaning of it contains a simple message: Black skulls were added separated from the others in the beginning of the last decade. It was a reaction against the mass killings caused due to Power Abuse in this time. However, I recall now that the wedding system was added at this time as well... It was a big deal because Free Accounts got finally a new outfit for the first time ever.
Having the choice to use the veil is a reference to the optional choice of marriage, added near to the time where Black Skulls were added in the game.