What made wow great was the sense of accomplishment.
Some mounts were below 1% drop chance, if you had that, you were unique, no mtx, no buying your way up (only gold)
Having to manually find people and go together to the dungeon you wanted to do just to find yourself in a massive pvp in the entrance between factions
Hours long alterac valleys, 10fps during intense battles...
Having some low lvl guild member ask for help because he's getting ganked by opposing faction, then immerse yourself into 1v2 or 3v2 battles
So many times I organized invasions, everyone wanted the warbear... We had between 100 and 200 people invading, multiple groups, it was madness
I left after the end of pandaria, but I think It started to go down when they came up with raid/dungeon finder