...and I feel fine.
Yes this is somewhat related to World of Warcraft : Cataclysm
Coming with the latest WoW expansion is something that I've personally only seen once before. A change of the worlds landscape on a major scale. Previously I saw this with The Bending in Planetside when the plaent Auraxis shoved its bits across the cosmos (and completely removed the Oshur continent in favour of Battle Islands).
That said, and I'm sure its happened more than I've seen, in any healthy game, the world ends on a regular basis. Well... the world as you knew it anyway.
How many shifts does it take though until the world you started in and the world you have now are only vaugely related in your mind? Old hands will always complain about how easy it is to level now, newbies wont know about aspects of certain areas and miss scads of story. Is this a move forward though? In some cases yes. I imagine Cataclysm will cause a wave of alts through the old content as people go to see what has become of what they grew bored of/outleveled. In other cases, I don't know. Champions had me go through two versions of two early zones. While they served as good introductions they're also misleading. The impression I got of Canada bore no relation to what the zone actually is. That sudden spike of awe was invalidated by the world changing so quickly.
Syp has posted over on Bio Break about the difference between convenience and consistency. Making the game easier versus keeping what the game was. Whichever wins out for each game, sooner or later the world changes. Let's just hope in the games you love, it's always a change worth singing about.