Keeping in mind this game was released in Japan in what... 2002? I think SE's done a great job keeping this many people attached to the game over such a long period of time, especially considering the average gamer doesnt spend nearly as much time on each title as they did back in the good ol' days (I still play multiplayer Doom on a regular basis, but even before that... christ, how many man hours were spent on Centipede?).
Re: Guild Wars. A guy I live with bought it and has spent some time playing it; it looked a lot less time-consuming than FFXI. If you're not engaged in battle, you can go to your world map and click on a city, and you instantly warp there. It does save the 15 minute choco from nation to nation and so on, but I don't think I'd like it much in XI.
There are some effing cool emotes in GW though, a lot that would look hilarious with a large party. You can dance, sing, play the air guitar / drums / some other instruments, do acrobatics, stagger, etc... and you just turn the emote on and it stays on. You could headbang to your air guitar for 3 hours if you wanted to.