Have to say that I agree with the guy asking the question. I never found myself needing to do a double take on a Blizzard trailer before. This may just echo what other people have already said but, my reaction to all the other expansion teasers: "Awesome, can't wait!" my reaction to this one "Huh? Wait, what?"
And to everyone that may be thinking "What's the big deal? You could play as cows before." I say this. Tauren are based off of minotaurs, so at least they come from mythology. In fact, most every playable race has been based off of, or influenced by something in mythology or Tolkien's work (with the exception of the Draenei). And the old races at least had some element of seriousness to them, except the Goblns, stupid Goblins.
Now tell me, which of these looks less like a joke?
http://us.battle.net/wow/en/media/artwork/wow-races?keywords=&view#/tauren02
or
http://media.mmo-champion.com/images/news/2011/october/art29.jpg
It's like the difference between Chewbacca and Jar Jar Binks, both are pretty crazy looking aliens, but one of them could be taken pretty seriously, and the other one just ended up being failed comic relief.
WoW has always had a tinge of silliness to it, but IMO it really started to go overboard in Cataclysm, with the Goblins and their astroturf, rocket car highways, pimp hats, and pleasure barges. Now come Pandas, with their goofy proportions, their big eyes and their stupid grins. Their visual design is even more cartoony than WoW's usual standards. WoW could have had something epic like The Emerald Dream, even Argus, instead it took another step in the wrong direction.
I probably would have come back for a while to check out the new expansion, if it was a good concept, now I'm just glad I jumped ship. So I'm not sure why I'm arguing about it on a forum, heh.