The best elements of the Cata leveling zones weren't the faction war if you ask me, but side-stories like Wrathion's cleansing or the actually funny meme quests like Welcome to the Machine and The Day Deathwing Came. In Hindsight Badlands was one of the few zones improved by Cata. Sure Deathwing and Green Jesus were crap, but then again in Mists I found the Mogu and Mantid to be the highlights of the story while Orc Hitler was, well, Orc Hitler.
To say nothing of total idiocies like Wrath's ''we're fighting together on the doorstep of the planet's most powerful necromancer? Let's kill each other after professing that was act to quell the unrest between the factions!'' or Warlords that doesn't even try to justify Ashran beyond there being some nondescript Ogre artifact that does things and thus we must send thousands of soldiers to their deaths.