Partnering with their unique machine friends, the Gnome nation breaks bad on the tallfolk of Azeroth. They are not going to take it. No, they are not gonna take it anymore. Be sure to check out the special guest appearance by Thrall and Jaina.
I would argue that they are actually more used in groups than in solo play, as raids check players for achievements when sell FFXI Gil, and guilds use achievements to rate where their proficiency. There are certainly still lots of things for solo players to do (every holiday, achievements come to the forefront again), but titles and mounts have become the main goals there, not just optional points. As Moonglade says, instancing and checking up on what players have done seem to have become the main point of achievements.