If I remember correctly, Vanilla wasn't about a linear lore progression as much as it was about you being that epic adventurer braving the depths of BRD and slaying the Alliance (FOR THE HORDE!). Yes it had some key characters but the lore in vanilla was based more around you and a your friends etc. I'm a huge fan of that. WoTLK wasn't bad until they added LFD, I'm a firm believer that's was the exact moment WoW started dying to me as an individual. I thought WOTLK was great at first but then LFD. It broke communities up, part of a server community was remembering who you went with into 5 mans, shit I remember people from Vanilla still and the coolest tank ever in my TBC raids (Eltorro, fucking badass Tauren Warrior).
WOTLK was strong up until then, WoW was an mmo now it's it's more like a do this and that and fuck community now.