I think that I will buy the expansion as soon as I get a pc that can actually run it. But I'm going to do it only because I have all the previous games and I really enjoy coming back to them every now and then. However, it will not be because I can't wait for it and expect something new from the game. I know what to expect from ANet - a rather boring lore with some interesting game mechanics. And I know that I will enjoy the product nonetheless.
Maybe that's your problem. GW1 has amazing lore and a lot of it is in quest logs. If you only read 5 of them sure you wouldn't know... The thing about GW is: You have to go out and explore/read to find the lore. It doesn't just pop up wherever you go. GW2 has the problem that a lot of lore/dialouge is put into events or timed voice-overs. It's pretty annoying to catch it even if you try to. That's one reason why I'm not a fan of voice-overs for this kind of stuff. Text is great.
Another problem is probably that a lot of people do things differently in MMOs than they would in RPGs. In single player games you explore anyways because that's what the game is about and you have nobody around to pressure you. In MMOs however people are driven by success. They want to keep up with everyone else so they feel that they have to go out of their way to explore if they could instead grind dungeons, speed level etc.