Nowadays there is no clothing piece on the earth which is only worthing for the female or masculine gender. Ask Marc Jacobs how can a man wear a skirt, or all those women fitted into a tomboy suite.
The same story again: No Rules.
The boyish jacket can be a perfect complement when you need to dress elegant but casual. A very simple piece which is similar to the LBD, it's always there for any occasion, and never gets old fashioned.
The same piece but different styles of women.