I miss the thrill.
I miss feeling like I achieved something after each lvl up.
I miss mobs who can fight us back and show us our place.
I miss grouping with other people to do difficult quests.
I miss spamming 'LFD xxx' then after finding group going there with another player, summoning other, getting a third of exp bar for entire run, not receiving a single item and single feeling damn good about yourself.
I miss ganking and being ganked.
I miss looking at that one player who has really awsome gear and thinking of him as some kinda god.
I miss being noob and helping other noobs in wow.
I miss the community, they atleast had some sense of humour and something interesting to say even when flamming someone, these days /2 looks like /b/ on 4chan.
I miss diversity.
I miss things that you had to put really alot of time into that wouldn't quite pay out, but still would make the player special.
I miss silly bugs that did some really funny things.
I miss the wow, not what's left of it today.