Hi. After you disabled the horde creation for new characters on Outland, many people will delay they decision to play. That move has been aimed to fix the Horde - Aliance ratio, but as for now, you just flipped the coin. Every lowbie is now Ally, which means 100-0 A-H ratio for low lvls now.
I am sure that if you have given the option to disable PVP righ after I set it in the game (not after 5 minutes or so), the problem of ganking would be gone. PVP server means you cannot disable your PVP in enemy/neutral territory. PVE allows you to do so in neutral territory, not sure about enemy territory.
Warmane team, you should open a discussion about this. If you have allowed to disable pvp in neutral and enemy zones (except capital cities) and maybe made alliance NPCs and Quest givers immune to horde attacks, it would solve the problem of players leaving alliance for horde.
Simply if I get ganked 5 times within an hour, then again when I'm waiting for the Quest giver to respawn (because horde killed it), it makes me sick...