You should also keep in mind that Oasis bases their Naruto Online set-up on the German server as well as the original. This means that they follow a similar time line when implementing new items to the game. If you look at the other country servers, there is no gender selection available. IF Oasis did choose to implement a gender selection set-up, it would likely be YEARS before it was done. Also, I believe if I remember correctly all mains and their jutsu were chosen and designed by Kishimoto. I would therefore assume that major alterations (i.e. gender change) would have to be approved by the man himself.