Oh god, this. Deathwing killed by Thrall because green Jesus. Pandaria introduced a bunch of new races and lore spread over a new continent. Main bad guy and last boss? An Orc in Orgrimmar, 'captured' by Thrall. Now we're trekking around the Orc homeworld experiencing stories solely concerning Orcs, waiting for the film about Orcs invading Azeroth (but seriously guys, they're hungry so it's ok, they're actually really cool guys).
It's not even that I'm predominantly an alliance player, I've split my time with WoW fairly evenly between the two factions, I'm just fucking sick of Orcs. Give some of the alliance something to do. Hell, I even heard that there are other races in the horde, if you can imagine such a thing?!