Today's Queue is inspired by things that are different. That is to say, we'll be looking at instances in WoW where one of these things are not like the other.
"Why do professions not level up at the same rate as weapon skills? I mean, weapon skills go up 5 at a time per level, up to a cap of 400 at level 80. But, once we reach master professions, we have to level 7.5 skills up at a time if we want to reach the cap of 450."
There's history to how the two skills got to be how they are, in terms of changes with patches and expansions. But that's kind of a sidestep to the question. What you asked is "Why do professions not work the same way as combat skills?"
The answer is that they're different systems. Combat skills function as a variable inside an equation and become meaningful when functioning inside that equation compared to your opponent's combat skill. By comparison, profession skills directly represent how advanced your character has become in a craft, and what recipes you can know.
The best answer here is "Professions and combat skills level differently because they represent much different aspects of the game."
"Does anyone know what will happen to a warlock's soul bags in Cataclysm, since the soul shard system is being revamped and the soul shards moved to under the health bar?"
They'll become something different; probably standard bags. Your shiny new soul-less bags won't be a slot-for-slot equivalent for soul bags, though, so that Blizzard isn't encouraging us all to stock up on bags before Cataclysm.
"Will Blizzard be allowing people to level their characters using the dungeon system when Cataclysm launches?"
I can't imagine why that would be different. You've always had the option of questing or just doing dungeons over and over. For all the window dressing, going into an instance boils down to just killing harder, different mobs. It's not actually all that different from "world mobs," except that you get private alone time with four other people.
"What is physiological difference between a forsaken and a human death knight? And if the answer is 'none,' then why have only human corpses become forsaken? Shouldn't all death knights technically be classified as forsaken (where forsaken are a fallen hero resurrected under the command of the Lich King and then somehow get their free will back)?"
You actually nailed it, there, Rainstorm. The reason forsaken and death knights aren't the same, treated the same, or have the same physiology is that they're different. If an undead and Forsaken were the same, then an undead couldn't become a death knight.
There's no amount of fanwanking I could do to convince someone who doesn't like the delineation, but I find it helpful to think of forsaken and death knights as simply being different critters. Vampires and zombies are both undead, but they can do wildly different things. Same thing with the forsaken and the death knights.
Have questions about the World of Warcraft? The WoW.com crew is here with The Queue, our daily Q&A column! Leave your questions in the comments and we'll do our best to answer 'em!