This has me going back over the past six years and realizing I've had to relearn tanking four times now. I had to learn how to do it originally in order to start working on Molten Core for my then-guild, and then I had to relearn it in The Burning Crusade (and actually, I had to relearn it twice there, thanks to the awful implementation of rage normalization for warriors and our astonishingly bad AoE threat that whole expansion). In Wrath, I didn't so much relearn it as suddenly find it much more efficiently designed and fun. Finally, Cataclysm has me tweaking how I tank, but I can't really argue I've relearned it from the Wrath era so much as simply refined it. Meanwhile, I've also had to relearn the DPS side of my class every expansion, in much the same way.
All of this learning has been done on the fly. To paraphrase a famous quote, World of Warcraft is vast and deep, and I'm swimming forever. Most certainly, there are sources to go to for players who want to learn a new role (one of them being this site), but there's only so much you can be taught before you have to hold your nose and jump in. This makes me wonder two things. First, is there more that the game could do to teach those roles, and two, would it be beneficial or harmful to immersive gameplay if it did?
At the same time, doing a quest line like the excellent one in Feralas where you and Ysondre team up against Lethon made me wonder if the game was holding my hand a little too much. I felt absolutely no sense of danger from this quest. I felt no fear of failure. And I don't know that it would really have prepared me for the actual feeling of running a dungeon if I were a new player.
Granted, with the dungeon finder so accessible now, perhaps it's not even necessary. Gone are the days when you had to stand around a major city spamming various chat channels trying to get a fifth to run Scarlet Monastery. Does the quest really need to do more than give you a cursory understanding of your role when you can put yourself into a real live instance almost at will? With people leveling as dedicated tanks or healers through the dungeon finder, it may not be necessary for the game to give people the stresses and difficulty when they can subject themselves to it at any time.
Frankly, Cataclysm improved the leveling and learning experience so much that while it certainly could add more innovations like the interactive maps, in the end, I don't know that going much further through questing would be ideal. Frankly, for all the pitfalls of throwing people into the deep end with the dungeon finder, I still think other players are the best way to learn what you're expected to do. The game can't stress test you the way four other people can, for good or for ill.
World of Warcraft: Cataclysm has destroyed Azeroth as we know it; nothing is the same! In WoW Insider's Guide to Cataclysm, you can find out everything you need to know about WoW's third expansion, from leveling up a new goblin or worgen to breaking news and strategies on endgame play.