Hi. I've been playing WoW on and off since it launched, and I've followed the online community (the forums) pretty closely for all of it, even when I haven't played. WoW is a gaming and cultural phenomenon; as someone interested in both, I'd be a fool not to.
MoP looks just like the past expansions: stylistically unique, lore-driven, increasingly streamlining game play and mechanics (this is NOT INHERENTLY a bad thing), graphically updated, and adding more for just about everyone to do (there is a noteworthy shortage of PvP information, but there's still at least a year in this expansion's development, so I'm willing to be patient - plus, since TBC, there has been an increasing tendency for the game to focus on story only growing each expansion, and PvP doesn't complement story as well as PvE does).
And, because of this, the community will INEVITABLY be in a massive tizzy up until release, when it will sell like hotcakes, and we all remember that it's Blizzard and they're peddling nerd crack so we have nothing to fear, it will be good.
A brief trip down memory lane of expansion complaints:
The Burning Crusade: OMFG Pretty blood elves in the hardcore Horde and space goats with no/horribly retconned lore for Alliance? Space aesthetics? OMFG Shamans to Alliance, Paladins to Horde? THIS IS THE END OF WOW, BLIZZ U KILLED WOW
Wrath of the Lich King: OMFG flying mounts? OMFG death knights start at level 55? SO IMBA! THIS IS THE END OF WOW, BLIZZ U KILLED WOW
Cataclysm: ...actually, I think that most people were alright with this one, come to think of it. There was a little complaining about how there were only 5 new levels and that the new races were "werewolves" (lol twilight) and the neutral goblins (although lore explained that one), and that the draenei got no new classes and that the Horde had one more race/class combo, but these were gripes, not doomsday scenarios. I think more people were excited about the old world cleanup, the new classes, and the dynamic story line visible through a changing world. Most of the end-of-world complaining came AFTER the expansion dropped, and THAT was definitely more than I'd seen before. Then again, Cata was considerably different from previous expansions - there was, for instance, no new continent - so the reaction was understandably different.
Now, with all that, does it surprise *anyone* that people are complaining about MoP? A race that can go to either faction, a new class, a new continent, a definite aesthetic, new casual game play options - this is much more in line with TBC and WotLK, and so it's not much surprise that everyone's calling doom and gloom.
The game will be fine. Insecure people afraid of playing a game with a less serious aesthetic than Cata, which had a theme of, oh, THE WORLD IS ENDING, will leave, and the game will be better for it.