Arkham, I am so much on the same page as you. GW2 is a game and every single game in the universe can be fun or un-fun to play, depending on how you play it.
I have a cousin who played professional soccer and he got to a level where he was demanded to play in a certain optimized way if he would continue his soccer career. He stopped. The game had been fun to him until focus shifted to optimization, then it was boring.
I do not think it is possible to make an MMO without players trivializing it. I think what game developers should do is to create the game they want to create. If people plays the game in a way that isn't fun to them, those players should simply stop playing. The rest of us can have fun until we don't.