Optimized it may be, but isn't [questing in Pandaria] just more of the same? With a new coat of (panda) paint, running on the same treadmill, with the scenery a little more scenic?
Well, yes. But the implication of the comment is that "more of the same" is a bad thing. I don't agree with that.
Novelty is not the only criteria for value. It is an important one, yes, but there are others. Execution is worth a lot, and Pandaria executes extraordinarily well.
It comes back to polish. The gaming industry drastically underestimates how important polish is. I think it's because different features are easier to justify and to advertise. Almost all modern games would be made better by cutting features, not adding them. Then spending time just cleaning up the small things.
I have a perfect example with The Old Republic. Ever since launch, two graphical bugs have been annoying me. First, when character select screen comes up, the current character appears shifted downwards. Selecting a new character immediately fixes it from that point on. Second, if you destroy something in game, the character model does not return to the default rest position, but is instead stuck in an awkward state until you manually pull out your weapon. They're utterly trivial graphical bugs, but I see them every single time I play the game, ever since launch. Seeing those bugs just reminds me that Bioware is not dedicated to polish as they should be.
Anyways, back to WoW. Yes, Pandaria is more of the same. If you are absolutely tired of WoW, then you're not going to like Pandaria. As for me, I really only have one character, so I only do extensive questing in WoW once every couple of years. So I'm not tired of it yet.
Pandaria is WoW, only a better, more polished WoW than ever before. Personally, I'm more than happy with that.