With only 2 "big" patches, it seems Blizzard wants to release faster expansions.
In my opinion, it's an error.
Players don't want faster expansions, they want more content. Or at minimum, they don't want 6-12 months of nothingness once the last raid of an xpac is released.
WoD could last 1, 2 or 3 years, it wouldn't be a problem if Blizzard would keep adding dungeons, raids, zones, quests etc. every few months.
Ok probably after 3 years we would want to explore new landscapes but still, my point is the following:
Designing a whole continent with specific lore is probably the most time consuming thing Blizzard can do. They're spending months or even years trying to get the best out of it, choose which mobs and vegetables to place everywhere, creating quests-chains to tell a story tie to this environment... and of course, hundreds (thousands?) of new 3D models.
Creating a battleground or a raid is only a tiny fraction of that.
But... instead of fully exploring this place (Farahlon or the rumored Ogre continent), instead of giving us new races to play with that would match this continent (Ogres & Arakoa), instead of letting us live in huge hubs (Karabor and Bladespire), instead of telling us more stories (especially with the Iron Horde)...
No: it seems Blizzard wants us to quickly level to 100, then spend a year doing the raids and then, bam! move somewhere else and forget this place.
The Iron Horde case illustrate very well this problem imho: It was supposed to be a major threat to Azeroth. An army of fearless warrriors, leaded by 8 of the most powerful orcs... And what did we get? The leveling was good... then we killed one as the first HM boss and 6 months later: the mighty Iron Horde was no more! Geez... All that for so little at the end? Why haven't Blizzard add extra quests/dungeons/stories every months or so to create some tension or telling us more about this organisation?
I feel like I only saw a very small portion of what Draenor could have been. What's the point of creating a new continent if you only scratch the surface?
Here's a tl;dr analogy: it's like spending 2 years building your own house and 6 months later, moving out to build a new one. Again and again.