I've been playing Horde for a long time. And even I have to admit, that the WoW, and Blizzard in general are pretty Horde-centric. When was the last interesting storyline that featured the Alliance? The Vanilla Onyxia chain? And Varian, the leader of the Alliance, at first he was watered down mirror Garrosh, now he's watered down mirror Thrall? He even has a similar backstory, slave to orcs, then escaped, sounds familiar...
When I was watching Blizzcon, plenty of in depth discussion and artwork on the Warlords, and what you are going to be doing with them there in Draenor. And for Draenei, one piece of artwork for a character, and promises they will have some really cool stuff?
You even see this type of thing spill over into Hearthstone, 4 Orcs in a list of 9 Heroes? Thrall, Gul'dan, Rexxar, Garrosh. Where's Velen? Where's Hemet Nesingwary? I suppose I shouldn't be surprised, the promo artwork did feature an Orc surrounded by Orc women beating a Gnome.
Is the Alliance just there so that the Horde seems to have some sort of punching bag or anti-thesis, so that they can look like the underdogs?