Unless I’m mistaken, the Devs themselves have outright stated they prefer writing for the Horde, that they find it more interesting to write for (granted this was before Golden became an actual member of the writing team, and only wrote novels for them). Of course, that doesn’t mean they write for the Horde particularly well.
MoP presented this fact to us in a very straight-forward manner. I remember when the Isle of Thunder first came out, some Kirin Tor NPCs/Quest-givers actually used Horde dialogue on the PTR, because Blizzard had just copy/pasted it over. The, ‘High King,’ questline we were supposed to get ultimate amounted to Tyrande being made a mockery of and then the Dwarves getting told to play nice. That’s to say nothing of the, ‘Robot Cat,’ fiasco prior to the Siege of Orgrimmar.
That there is a clear passion for one faction that is found lacking in the other is quite obvious.
Though personally, nothing will ever quite top the atrocity of, ‘Void Elves,’ in my book. How that ever got the green light I do not know. You can’t even call that, ‘lore.’