They're not letting you change anything that impacts anything that your character has done in the past, gender is technically just another cosmetic of you appearance. If they start allowing people to change their race and/or class then you're seriously changing the code against that player.

I'm sure it could be done if they said "ok we'll let you change faction or class but all that you'll take with you is your bank contents, gold and any gear that is a either a drop or quest reward for both factions", also "Quests that are faction specific ie: not handed out by a neutral NPC will be erased will may result in the loss of a title". You could obviously go and do these quests again under your new faction since they'll be 100's of NPC's with !'s above their heads in all major towns and cities. Then there's the HK's, pvp gear and mounts that you have from the endless killing you've done against your new faction. Surely your reputation should come across as hated amongst all major factions.

Think about it, changing faction involves a hell of a lot more than just giving yourself ponytail and a cute ass to replace those squids that you used to have instead of a chin.

That’s not to say it won’t happen in the future but for those that say it should be free need to think about the work involved in making these changes. If it was free then you’d have 10 million people wanting ALL of their toons changed in some way or another.