I've said before and will say again that quests like Welcome to the Machine demonstrated real mastery on the part of the development team behind Cataclysm. To my mind, the real lesson of the Cataclysm to Mists transition is threefold. Cataclysm was extremely well designed, but the majority of its best content is in those revamped 1 to 60 jones, or to coin a term, is in vertical content, a pillar of content that players ascend. Mists content is horizontal -- while there are several zones to level from 85 to 90 in, the true flowering of the vast majority of Mists content is a plateau, an expanse that blossoms outward. Once you ascend those five levels, you get more to do, not less. However, it must be said that this isn't a trend that Mists invented. Pretty much every innovation in Mists of Pandaria's content delivery is built on the edifice of Cataclysm, which itself built on previous expansions.
Expansion aren't developed in isolation from each other. The people who made Cataclysm made the game you're currently playing -- the hallmarks of daily quest hubs like the Shado-Pan in Townlong or the variety of quest hubs for the August Celestials can be felt in the Molten Front offensive's gradual unlocking and the Argent Crusade both before and then after the Argent Coliseum was introduced. The real change this year was in fact somewhat of a regression combined with what was learned in Cataclysm - Pandaria goes back to the new, continuous place to explore with new zones all physically connected pioneered in Burning Crusade and Wrath of the Lich King. Meanwhile, without the burden of an incredibly expansive redesign for the entire world, Pandaria could focus its efforts on enough questing content to get you from 85 to 90 and then blow the doors off with content for 90, instead of spending so much of its time on complete revamps. Some of the questing content in Cata was the best questing content ever designed, but it was content that not many people would see, aimed at levels players do everything in their power to skip over.
In the end, Mists solves this problem by simply not having to solve it. The previous expansion already did all that heavy lifting, updating the game and its world for the next few years. Mists was in effect carried to the top of the hill by Cataclysm and gets to rocket down the slope benefiting from that hard work. But it also definitely puts all of its effort into being expansive, both in terms of how it feels to explore and experience the world (which you can simply do) and in terms of all the new systems there are to experience. Pet battles don't just involve flinging the contents of your pet tab at each other, there's systems to interest you in exploring the world and seeking out new pets, even in old familiar places. Challenge modes remove the gear equation, forcing players to focus on doing their absolute best. Even the positioning of the PvP and PvE vendors forces players to get out and see what they're playing in.
Will this solve the kinds of doldrums we saw as we waited for Cataclysm to end? It could be said that from February to September, players were mostly waiting and waiting for Mists instead of really playing the game they had. If Mists can continue to deliver patches with the speed it did 5.1, it's hard to imagine entering that sort of dead zone again, but 2012 shows the danger. We not only need a wide variety of content, and we not only need it focused at the max level player, but we need it fairly frequently.
Mists of Pandaria is here! The level cap has been raised to 90, many players have returned to Azeroth, and pet battles are taking the world by storm. Keep an eye out for all of the latest news, and check out our comprehensive guide to Mists of Pandaria for everything you'll ever need to know.