Where's your evidence of this? Anecdotal? Don't cite me the arena ladder, because if you're going to try and tell me that represents the entire part of the community that does PvP, I'm going to fall out of my chair.
Even if it were true that EMFH was so good for DPS specs that it guaranteed a win for those players, it's nearly useless for Disc & Holy Priests and Holydins. It's not even an option for RDruids and RShaman.
TIL Arena rankings was the end-all, be-all of faction balance.
If a racial causes most teams want to choose a certain race/faction, then that's fine, so long as the factions overall reamain balanced in terms of population and activity. Which, aside from the arena ladder you like to cite so much, is pretty well balanced overall.
What issues? The low representation of Horde in the arena ladder? You don't think that a custom change to the racial could have larger ramifications than the "balance" of the top of the arena ladder? If that's the case, then you're definitely rather short-sighted.
Arcane Torrent shouldn't be forgotten, either.
I'd say you're vastly overestimating how much they care about such a negligible difference in stun DR and damage.
I'd also say you're underestimating the value of the stun CC type.
Feel free to explain the downside of having the Orc racials for a spec (RShaman) that would normally use a resilience trinket anyways, nevermind that the spec isn't even an option for Humans.
Perhaps useful in 15 times as many situations? Sure. That doesn't make it 15 times better. How much more useful is EMFH going to be for you when up against a dot cleave like AffLock/SPriest? It's not.
"Oh but it's useful in all these other situations."
But that's not how top-end PvPers min/max. They min/max on a fight-to-fight basis, not trying to grab what is useful against the majority. That's the approach of a BG hero. Especially when in a lot of comps that would be run, half the team doesn't even benefit from EMFH (cough healers).