After some debate in the forums, I've found a better way to frame what I consider to be the revolutionary quality of GW2, and why a lot of players just aren't seeing or feeling it.
ANET's game philosophy with GW2 started with conceptualizing a new social contract between players, and then from that fundamental premise constructed - either from scratch, or by using new and old MMOG functions and structures - a game that would fit and promote that new social contract.
This, IMO, is what is truly revolutionary; ANET''s design concept was first about finding a way to change how players felt about, and around, other players, and also how the game affected the players. You can tell this by seeing how everything in the game, from the ground up, is organized. They wanted to create a new, more upbeat, helpful, tolerant, equitable and fun social contract that was fully endorsed and motivated by game mechanics. ANET didn't want to foster any significant sense of elitism, exclusivity, ostracization, or reward playstyles that were essentially based on dividing the player base into castes.
I've never seen another MMOG developer do this; start with kind of social contract they wanted to exist in their game (both between players, and between the player base and the developers) and build a game from the ground up based on that concept. No, this doesn't mean every aspect of GW2 is new, or revolutionary, or inventive in and of itself; much of what ANET uses in GW2 are fairly standard fantasy tropes and MMOG conventions, which would leave many walking away wondering what the heck everyone else was so impressed about.
What the big deal is (or at least one of the big deals), is that many of us have yearned for a game that promoted a different social contract, one not based, essentially, on envy, distrust, high-efficiency min-maxing and which celebrated countless hours spent ATK grinding repetitive content.
And that's the real, unique feat that ANET has apparently (through BWE, anyway) pulled off; they really have created a game that establishes and promotes an entirely different social contract, one that is, IMO, far healthier and more positive than most others. It celebrates working together, it doesn't force it. It rewards the helpful and explorers. It has made every other player on your server your ally. It fully supports the individuality of character builds and styles. It doesn't prod you to go where you do not like to go, or to do what you do not want to do. It embraces fun and doesn't uniquely reward anyone treating the game like a 2nd job. It doesn't make you feel like you're wasting time or putting others at risk. You are always rewarded appropriately for your contributions. You do not have to choose between loot/resource nodes and not being a jerk.
Do other developers even consider what effect their game mechanics have on players, or what kind of player interaction they are promoting? It makes me wonder.
Job well done, ANET!