Five days now and while I'm slowly working through the Blizzcon announcements I haven't even reached the one feature that might very well change everything. Tomorrow perhaps. First, I'll write about the announcement to make MoP feel more 'light'.
My mood while playing Cataclysm is almost exclusively determined by the colors of the environment and the sounds. And looking at these, Cataclysm had light and dark zones; just like all other expansions. That's a good and balanced design. But it really has little to do with 'seriousness'. You can absolutely make a dark zone that is completely silly. Just like you can make a light zone that is very, very serious. For example a temple. A serious zone can, by the way, include funny elements. If they are used in moderation they can add to the experience without making the rest of the zone look silly. Using “concentrated coolness” in moderation has, of course, not exactly been Blizzard's strength in recent expansions.
I don't really understand in detail what Blizzard means when they say that MoP is going to be more light. I understand it superficially, but if you ask me what that actually means, I just don't know. Is dying disabled on Pandaria? Do Pandas kill you and then drink a beer on your corpse, while the Undead kill you and then spit on you? Sorry, now I am being silly. World of Warcraft is fundamentally about killing things with your character. And death is not light. You can make it silly, but not 'light'.
My conclusion on this topic is that these are words that sound like they mean a lot, but are ultimately empty. But if you think that you understood exactly what it means that MoP is going to be more 'light' and how that translates into my actual gaming experience, please let me know.