Tirion is neutral. Horde did the same amount of questing with him from classic wow. Even when he was on duty, he wasn't in the Alliance we know of today. The fact he's human is all that people can go on. Race shouldn't automatically make someone Horde or Alliance.
Brann is pretty much neutral too. He shows up for an Alliance quest because it's related to his brothers. Otherwise the Horde interact with him just about the same.
Arthas was never part of today's Alliance. Same point of 'human doesn't equal Alliance' comment goes here. Rhonin too to some extent though he did convert to being neutral full time with the Kirin Tor leadership.
Jaina was the only character I could find from your list ( unless I missed a post ) that is now 100% Alliance. She did try to extend some kind of diplomacy with Thrall. Years ago I wrote about her and the neutrally issue but that simply isn't the case anymore.
The Horde have the same quest line pretty much in Grizzly Hills? With that one chick you save and help her sister, yeah? I can't recall Grizzly Hills being too different when I went through as Horde. I don't recall much of WOTLK being so different save for the starter quests and Wrathgate. Wrathgate was the biggest Horde/Alliance attention given in the expac. The rest was focused purely on an equal scale of fighting against the Scourge.
We might have had cool heroes. No doubt. They're now mostly dead, neutral, or both. Jaina honestly is a rare one in this day and age of Warcraft lore.
Honestly, I think this is just a more specific, overarching complaint about the "more things change, the more things stay the same" aspect of MMOs. For those that care about story and lore, the idea that wonderful and terrible things happen (the death of gods, the raid of cities, invasions, etc) and leave NO mark on the world smacks of careless planning by developers. Additionally, more and more the lore is being subverted to conform to the needs of gameplay mechanics. The problem is, you could develop the lore AROUND the gameplay mechanics, which would seem more natural inside the game, or you can try to make whatever lore you believe is "cool" and then just ignore the outcomes in the game itself, which feels stilted and lazy. The same issues have occurred on both the Horde and Alliance side. To be honest, the entire idea that we have sufficient resources to continue a perpetual war is kind of ridiculous, and there really isn't a coherent understanding of what the hell we're fighting for on either side anymore. Additionally, we've grouped together to kill OLD GODS. At this point, the "war" between the sides would have demolished all the cities and areas already.
I wouldn't hate if 5.5 or 6.0 explored the possibility of a temporary cease fire due to the ending of 5.4. You could easily write off world PvP as unauthorized border skirmishes, etc. Sure, you could end it later, but it would be a welcome change of pace to see the opposing factions in capital cities WITHOUT PvP, even for a small amount of time.
MoP and Cataclysm are considered Horde-centric by a lot of people because the Alliance is always responding to some Horde action. The Horde is damn near always the initiator, while the Alliance is constantly running to try and catch up. With the Horde steamrolling over Alliance territories with very little counter-attack in Cata, and then setting itself up for conquering Pandaria and making the Alliance scramble to try to defend it in MoP, there are really not a lot of moments where the Alliance can say they took the initiative. Even the Siege of Orgrimmar is being set up by the Horde itself, with the Alliance just in for the ride.
Trying to argue anything with any sort of nuance over Twitter is the intellectual equivalent of trying to trying to squeeze a cow through a keyhole. Sure, you might even be able to do it with enough brute force, and whatever comes out the other side might even still be considered to be "cow" in the technical sense, but it will be so mangled as to be completely unrecognizable.
"I was a normal baby for 30 seconds, then ninjas stole my mamma" - Deadpool
"so what do we do?" "well jack, you stand there and say 'gee rocket raccoon I'm so glad you brought that Unfeasibly large cannon with you..' and i go like this BRAKKA BRAKKA BRAKKA" - Rocket Raccoon
Originally Posted by Blizzard Entertainment
OK, new idea. Let's just all get along, spread love and cheer and joy, and be one big happy faction!
We shall be known as the Alliance of Happiness, and no one can say Horde bias to that because Horde's not even in the title, but Alliance is.
I stopped caring about faction favoritism a long time ago. - alliance
Originally Posted by KungFuFanta