Earlier quoted context omitted.
This was my first thought too. Although I must admit I didn't play WoW until the release of BC (Burning Crusade) and stopped when Cata finished. So I never really got to experience what was special about Vanilla. More specifically for why I'd want WOTLK is for Arena. The last season was the most balanced that I ever experienced it and some of the most fun I've ever had playing WoW or any game in general. Jumping back…
But it will be very, very hard to keep that experience. Where you used to have to turn to other players for help, building those social relationships as they struggled through the same challenges, now the web environment surrounding the game has evolved with very complete documentation an alt-tab away, and all the other players have that as well.
Edit: words