Population imbalances really, really suck. I think it might be payback for playing Albion in DoaC. Course it wasn't until Blood Elves were released that the Horde became so numerous. All horde are closet homos.
Or some of the girls and closet homos on Alliance side jumped to Horde because blood elves (on both genders) look just effeminate enough to please both parties. And probably because they didn't want to have the "offensive" stripper dance.