There is a contradiction at the heart of the old world revamp in Cataclysm. On one hand, the mechanics are more newbie-friendly, to the point where even a lot of experienced casual players are saying that it is too easy.
But on the other hand, the stories being told are not particularly newbie-friendly.
Take Westfall for example. The new Westfall is a tour de force. It is gorgeously done, and a joy to play through. And yet, would it work at all if you hadn't played the old Westfall? If you didn't really know who Edwin Van Cleef and the Defias are?
There's lots of zones like this. The reclamation of Western Plaguelands is also a great storyline. But can it work if you didn't see the original Western Plaguelands?
Darkshore is heart-breaking for an older player. But again, not experiencing the original Darkshore causes that zone to lose a ton of impact.
The same thing is going to happen with a lot of NPCs. Their "origin story" disappears, but the NPC is still in the world. For example, take Chromie and Tirion Fordring. Fan favorites, both of them. But the original quests which introduced you to them have been removed.
To me, the level 1-60 zones in Cataclysm now feel like Book IV in a series. But Book I is no longer available to read. And Books II and III now come after Book IV, for some reason.
But then again, maybe I'm wrong. Maybe new players won't be hampered by this fact. Or maybe it will feel to them like the world has history. I mean, I never played Warcraft III, and I never felt that I greatly missed anything.
(Except for Illidan. I never really understood what the fuss about Illidan was all about.)
Of course, one significant difference is that Warcraft III is still available for play, while the original zones are gone for good.
I am not sure that--if I was in charge of an MMO--I would ever green-light a revamp like Cataclysm. I actually agree with pretty much all the mechanical changes, and even the easier difficulty. But I would balk at rewriting the original stories of the game. Even though the new stories are extremely good, I think the loss of the old stories was a greater harm.
Of course, going through the older stories and tightening them up is another matter. In some respects, my ideal change is something like what happened to the quest [Princess Must Die]. The pig, Princess, used to be on the other side of the map, in the Brackwell Pumpkin patch. It was moved to the Stonefield farm. This made it easier to complete the quest, and strengthened the original story. Before, you were sent to assassinate a pig on a different farm, which was somewhat questionable. Was the pig really causing damage, or was Ma Stonefield using you to hurt an innocent competitor?
While now the pig is clearly causing damage to the Stonefield farm. The story is tightened up, and mechanically life is easier as you don't have to run to one end of the map and back.
In a lot of respects, I think Blizzard should have kept changes to the original zones to that level. Edit Book I rigorously, but not replace it entirely with Book IV.