While I think this is a good move, I don't see why Blizzard doesn't take this further. I must admit that I don't really understand Blizzard's aversion to spacing out content.
Why have this giant glut of content right at the very start of the expansion? It seems to me that when all the content is front-loaded, we just end up with larger and larger gaps at the end of the expansion. Take the tail end of Cataclysm. It's been eight months since there's been any new content.
Why not release Pandaria without any raids? Let everyone go through all the leveling content and the heroics. Two months later, release the first raid. Two months after that, release the second raid. Then two months after that, release the third raid. That gives lots of time for Blizzard to add new content into the game, while still giving everyone something new to look forward to every couple of months.
It seems to me that a steady stream of content would be more interesting that everyone gorging themselves at the beginning of an expansion, and then dying off at the end.