Horde doesn’t need your examples or logic. Or even raid log numbers from Ironforge. Pro or Arena stats from
drustvar. com/tbc-leaderboard/stats/eu/2v2
All they need is HvH for fastest queues and Faction balance is too long solution for them. Besides they enjoy current state of the game where all joining players are not evenly split, but go for the Horde by default.
There is no way to encourage more people to play alliance, not until wotlk at least (but that will be the pvp metaslave population of the horde, which is around 10% at most). The alliance attracts pve-oriented playerbase mostly, people who are usually not in the slightest interested in pvp. It has to do with the lore, the aesthetics and your own fantasy. There was a reason for draenei males in TBC - unique looks (that differ from differently sized and shaped humans) and orc-like muscles.