Vanilla was hard and slow. It sounds awful, but it meant that you basically had to group up to get anything done. But everyone knows this, which makes it incredibly easy. People ask for groups for the harder quests in trade chat. All the time if you see someone griding the same mobs as you, you group up. They finish the quest first, but usually they stick around to help you too. Then you feel like helping other people. I asked for directions to a quest objective in general chat (no blue map blobs) and someone took the time to physically lead me there. You don't get this anymore because the map tells you where everything is and the mobs die in 2 hits. You can do everything super easily yourself, so why bother with other people?
Also class quests were awesome. Fire totem means so much more when you quest for it rather than having it pop up on your actionbar.