Its really ignorant to believe that a world needs to be persistant for it to be an MMO and with out persistants, its not. Unless you are the one who coined the term, I wouldn't argue with you, but since I'm 99.9*infin sure that you didn't not create the word MMO its all open for debate. And not all areas are created on the fly, all the hubs are persistant with persistant AI doing thier job regardless if people are there are not, so just because playing areas are instance and not persistant, can we easily toss the MMO title out the window disregarding the
hubs? The hubs sound like just any other town in any other MMO. People stay chat and AFK selling goods or resting, out in the killing fields mobs are killed and respawn. Doing nothing until somebody comes by to kill them. How much different is GW by not having those mobs in the first place until it needs to create them for an adventure? You don't know that they are there until you run up to it in any other "real" mmo.

From wikipedia.org:
The boundaries between multiplayer online games and MMOGs are not always clear or obvious. Neverwinter Nights (2002) and Diablo II are usually called online role-playing games (RPGs) but are also sometimes called MMORPGs (a type of MMOG). Guild Wars has been called an MMORPG, but most of its gameplay involves small groups of players in private areas. That game's developer prefers the term "competitive online role-playing game".

Even tho at heart is a CO-RPG, it has a lot of elements that make up MMORPGs. Saying GW is not a MMO is like saying a cat with only 3 legs and no tail is not a cat because its missing a few parts. Would it be more "correct" to call it a COMMORPG, sure, but it's not wrong to just call it a MMORPG in short. Its doubtfull that CORPG is going to catch on. MMORPG in short, means any rollplaying game that is done oneline with massive ammount of players. While the players may be massive (one total server-spanning across many zones), playing against is not as battles are limited in total to 64 max (8v^2) currently.

Nit pick as you will, and i'm sure you will...

BUT WAIT: World of Warcraft has instance dungeon such as Blackrock Depths or Scholomance. SO that must mean its not a MMO!! To your logic, that's the difference between a MMO and a non MMO. /sarcasm