Unexpected but understandable.
The biggest problem I see is that WoW doesn't attract new gamers. It repels them. The opposite used to be true.
The difference is that new players start on the 1-60 experience, then ram headlong into the Cataclysm revamp: a disastrously mishandled, ultra-linear rail rider. Then they quit. It's an in-game tribute to itself, whose in-jokes and nuances are incomprehensibly alien to anyone who hadn't played since Vanilla. It's exactly what you'd do if you *wanted* to make the game only accessible to long-time players.
[Example: Does a new gamer care who Mankrik is or how the Banshee Queen makes more doodz? They want a world of possibilities. They get "kill 10 boars. Now kill the crown prince of boars. Now go to the next whistle-stop and do the same again." They go play Skyrim instead.]
Be honest with yourselves...if you had to do the current 1-60 climb more than once, would *you* keep playing? I wouldn't. I leveled alts because I had things left to discover. Now Azeroth feels bland, boring, and sterile. Leveling my Monk, I nearly rage-uninstalled. I *couldn't* do that again. The world, frankly, needs another revamp -- keep the zones that needed reworking (here's looking at you, Badlands, Desolace and Felwood). Revert everything else (Barrens, Tanaris, Searing Gorge, for God's sake Feralas and Thousand Needles).
Very secondarily, Mists of Pandaria is two disparate game systems tenuously linked together: An excellent, better-than-ever leveling game from 85-90, with an endgame that's raid-focused, gear-dependent and demanding. The transition zone is daunting enough to be a dealbreaker -- even to people who did endgame content in old expansions.
[Example: My guild lost several new 90s to this -- people who won the game with us during WOTLK. By that, I mean "Light of Dawn", not "Kingslayer", roughly 200th US/1000th world, and our server's first. The transition is *that* daunting. People who wiped to H LK 25 with me for 4 months found it too tedious.]
The biggest culprits are things even Ghostcrawler admits were flawed: mandatory dailies and double-gated Valor rewards. Those changes were due in 5.1. Changing them in 5.3 is too little, too late -- though, still better than the loot shower of HoT/ICC 5-mans.
That Blizzard feels the need for a gearing guide, and that the guide itself is such a tangled mess, is *precisely* proof of concept. Blizzard needs to do two exercises with that gear guide: (1) make an alternate "gearing plan" that they *would've* adopted if this expansion was released when 5.3 came out...and (2) make that their plan for next expansion. This kind of clumsy, half-hearted ret-con speaks of game-breaking short-sightedness.