Agreed completely with nostalgia. Between the contents of my earlier post, and what you said about nostalgia, it pretty much covers what Jobbu said was his hook for WoW.
For me personally, nothing will ever beat playng runescape with a couple of reallife friends.
Mining together, getting killed by that random chicken, doing those complicated quests together, it was so simple and yet so satisfying..
I must say I will have some nostalgia about GW2 in the first weeks too.
Yes it had its problems (guild chat, TP,..) but the player activity, the map chat, doing DE's with 20-40 people, people helping eachother with the hard vistas and jumping puzzles.
I think I will remember that for a long time.