Yet Blizzard released Outland, which is not much bigger (and may even be smaller) than some of the planets and THAT was OK? I heard no whining about that. How about WotLK, which offered Northrend? That wasn't much bigger.
Outland and Northrend may not have been that much bigger, but they continued WoW in the vein that people wanted, in that they brought more raids to the table. Makeb misses out the one key selling point of this game
No amount of size is going to change that fact.