When tbc was new it needed a second starter zone, now since you can skip it easily anyway and there's far fewer people its just not needed. As for MoP, the factions are very spread out so it wasn't really needed there either. Though a second option would have been nice. Ideally they should've made Krasarang a starter zone too, but you would need a similar 'well we screwed up' ending to make the story work.
My initial thought was "Sure, another zone or zone quests in one or more could be lowered and make for less 'You must quest here!'" but then I realized that I usually pick the same zones anyway. While yes, it's boring sometimes, it's also a lot faster and more efficient to level where you know vs trying to figure out where to go/what to do.
On the other hand, my main influence for voting "it doesn't matter" is Cata starting zones. Hyjal i just better and easier for me than Vash. As much as I might even like aspects of Vash, I'm just too disoriented by it all. So maybe I should have said "Yes, more zones = better. Just don't make them gimmicks." *shrug*
On a scale of 1 to Voldemort, he's a "Doesn't have a nose, but doesn't know Evada Kedabra." - RAGEface14
I hope they redo 60-70 content soon. I don't know if Outland will be redone in the next expansion, but maybe after seeing the success 1-60 changes had they could maybe do some 60-70 content on Azeroth somewhere that is relative to whatever the xpac is about.
Of course it'd be weird going from "OMG the world is gonna be destroyed!" to "New content" to "Lich King" to "OMG the world is gonna be destroyed!" to "Stop the Sha, Save a Pandaran." to "New content".
http://i.imgur.com/pXxTP.gif The greatest trick ever played was man convincing himself that God does not exist.
On the one hand the idea of more variety would be nice
On the other doesn't everyone always just do Borean Tundra and Hyjal anyway? When you put options in all you're accomplishing is getting people to do each of them once, after which they'll level every subsequent alt in whichever zone is more convenient. Howling Fjord takes longer to get to from your capital city (especially if you play Alliance) and is full of obnoxious hard to navigate cliffs, Vashj'ir is underwater. So they get skipped.