I have mostly been a PvPer since the beginning of Cata, however I still keep up with the lore. I have read most of the books and I am really into the lore of each race/class. I'm also not really a fan of the last two expansions, and even when I clear my mind of nostalgia I feel like I had more fun in Vanilla, BC, and Wrath.
However, the last two expansions were necessary from a lore standpoing. Let me explain:
The Lich King was the end of the major story arc that has driven the Warcraft universe. Many would say the game should've ended there, and that is mostly because it really was the end of that story. Now, with the end of the LK story, the only place they had to go after that was the conflict between the Alliance and the Horde. Realistically, a war really couldn't be started with Thrall at the helm of the Horde.
So, since Thrall pretty much couldn't be the warchief as he realistically wouldn't be coaxed into a war with the Alliance, Cataclysm was really just a filler expansion to remove Thrall as the warchief of the Horde. Deathwing was only there to destroy Azeroth's continents and rid the Alliance/Horde of what resources they had, leaving both sides starving for resources. It wouldn't have made sense for them to put Cairne or Vol'jin in charge of the Horde when Thrall left, so they had to put in a hothead like Garrosh. It was the only conceivable way that they could start a war.
Enter Pandaria. Pandaria offered the new resources that both sides would need to rebuild after the long wars with LK and Deathwing (who destroyed their home continents). Resources were an easy way to get both sides involved in the war, the same way that real wars often start over the same thing. Pandaria as the location for the continent was probably the most logical choice out of the whole WoW universe, as I can't really dream up a new continent for them to fight over resources. The Horde/Alliance get pulled into the ongoing Sha conflict on Pandaria, and deal with that problem, which eventually leads to the demise of Garrosh as warchief and Vol'jin taking his place.
Now both sides are at more ease with each other, and I expect a lot more out of the next expansion or two. It should go back to it's roots. The Alliance/Horde should once again have a common enemy in whatever big boss they bring out for this xpac (preferably Burning Legion related).
So, lore-wise the last two expansions made sense and were necessary, but I personally wasn't a fan of them. But, knowing that I didn't enjoy them as much as the first 2 expansions, I also understand that it was a necessary story-point they had to visit before we could move on.
Everything leading up to LK -> Deathwing destroys resources -> Thrall is called to be the aspect of earth -> Garrosh the hothead takes over -> Pandaria is discovered and the war for resources between the Alliance and Horde begins -> Garrosh falls and Vol'jin takes over -> Hopefully another common enemy for the A/H to conquer