adults grow up but new players keep coming in. your saying that they won't enjoy what other people enjoyed then? it's not like they are adding a twilight and vampire diaries theme to the game. though i wouldn't put it past them either lol.
you are right though, it's like heroin your never gonna get that exact same feeling as the first. but it does have to do with how the game is produced and who it's produced for. mmo's are short lived. and as year goes by you'll realize your paying monthly for an offline game with people in it.
as for the 16people killing crabs over literally just running around spot to spot doing quests that you don't even read, yeah huge difference but i like the crabs with 16people to roll with over ..solo'ing quests. if i want to enjoy flowers they won't be of the digital kind. but either way i bring up ffxi again, but lol that game had so much exploring in it. the problem people have is that leveling is separated. witch only helps layer a mmo more.
it's not nostalgia or age that keeps you from not liking other mmo's anymore. read all the threads in every forum for every mmo. either way it's about cash and how people are side lined out of there own enjoyment to sqeeze more people and profits. just like someone else said earlier this is happening with tv and movies too. can't enjoy even a syfy series without it trying to grab other types of audience by adding filler and garbage to it. or using the same name of old just to get old and new into it. in the end we are all getting half of what we used to.