I play Alliance now. I've played Alliance primarily throughout my WoW career, although admittedly I played Horde over on Malfurion with some awesome folks local to Edmonton (Hi Vees) and again on Sisters of Elune with another group of people I really liked. (Hey Taken.) When I played Horde, I almost always played tauren because, well, I have significant problems with Horde storylines. My then-fellow Horde would always tell me about how they liked the Horde's underdog status, but I never saw that - I saw forsaken plague bombing people, orcs attacking their enemies when they were occupied fighting the Scourge, etc etc. The Horde was always the aggressors, I noticed - how were they the underdogs? Still, I liked the people I was playing with (still do, in fact) and so I kept going. Just because I didn't see the underdog thing didn't mean it wasn't real, and there are plenty of other reasons for faction preference.
Still I ended up back in the Alliance, as I always knew I would. I'm a draenei again, like I was in Wrath of the Lich King (and frankly, often in the same outfit) and I will admit here to favoring the Alliance in storylines. The Alliance is simply the group I sympathize with more, and Cataclysm definitely gave me plenty of fodder on that front. I know a lot of the changes were made to balance the Horde/Alliance leveling experiences, which were infamously disparate. It still ended up feeling like the Alliance was playing frozen side of beef in the Horde's upcoming "I did it, Adrian" montage. While I've since really enjoyed Mists of Pandaria, it hasn't entirely rinsed the bad taste I got leveling an alt through the Cata 1 to 60 game.
So it is from that perspective that I have to say that I don't really understand what, exactly, some Alliance players want to be the outcome of Patch 5.4 - it seems like all that will satisfy some players is the complete and utter destruction of the Horde and the uprooting of half the player base.