Consistency of world =/= storyline. I don't see anybody worth the weight of their flesh complaining about "OMG EXERCISM WON'T CRIT UNDEAD PLAYERS EVEN THOUGH THEY ARE UNDEAD."
In fact, certain spells working X way against the undead is a gameplay mechanic. So that's a gameplay mechanic trumping a different game play mechanic for the sake of pvp balancing. Unless it's written in one of the novels that "The Hunters humanoid tracking ability also shows undead players". Otherwise the way certain spells interact with certain creature types isn't a part of the lore.
And the point is that every time somebody points out the obvious reasons why MoP's storyline failed at life, people devolve into a "Gameplay > Lore" fanboy chant.
And then the Zandalari role was laughable. Seriously. They need to stop including the Zandalari unless they are going to move that plot arc forward. It has gone nowhere. "We be restorin' the old empire mon, now fight some giant trolls and dinosaurs"
All of the tie-ins to the "central plot" of WoW felt like they were added as an afterthought to quell the complaining about derailing the storyline. And even then "Mogu = titan constructs that were corrupted. LOL" Titans built shit, and shit got corrupted. Again, absolutely no plot progression on that arc. They just reiterated it, like with the Zandalari.
The silithi... I mean nerub... I mean mantid, bug men worship old god, let's beat up corrupted bug men. The fact that Y'Shaarj was dead and his heart was in a box and that Garrosh could steal the heart and use it as a weapon... very very minor plot progression. But then we make the heart stop beating and he escapes and makes new orc models on alternate past but not past because it's not a time travel expansion Draenor. And somehow on the concept art they managed to make the Warlords look all cute and cuddly.
Vanilla introduced the story arcs, TBC through Cata advanced them. MoP stagnated them in favor of introducing a new story arc, despite the fact that the Legion and Aszhara story arcs haven't even been resolved yet to within any degree of satisfaction. So despite the lame ending for Cata, it at least saw the decimation of the twilight cult.
In fact, any story arc that MoP touched, besides the Garrosh arc, was just a shameless reiteration for the sake of fan service.