Crappy painting skills aside, here’s a graph explaining my point of view of good MMOs.
A really awesome MMO isn’t about single player experience (TOR comes to mind) and a really good MMO isn’t only about group content (EQ for the most part). MMOs are awesome when both of those interesect.
Back to EQ for a second. People are going to clamour that EQ was a great game and in some parts it was. It did drop subs like a brick once WoW and EQ2 came out though, so there were obviously some issues with it and they mostly surrounded the group aspect. What EQ did right was find the balance between personal story/responsibility and group content. Meaningingful consequences to your actions (such as faction gain/loss) affected not only your group’s ability to progress (gated content) but also your ability to progress (say enter a city without being KoS).
WoW Vanilla did this too, to a degree. It opened up the intersection of the two parties and really rewarded group play while keeping the single player aspect alive. You could do something meaningful in 30 minutes. This simply has never been the case in EQ. WoW today however, focuses much more on the single player aspect. LFD/LFR are all for the “what about me” generation, with quick rewards. If you don’t like it, leave ’em and try another one. Guild levels don’t provide any type of group reward. Enter any city without a guild and you’ll get 100 invites an hour to a 25 guild.
The success of the next great MMO will be about finding the balance of group content and single player content. Hopefully the ship can right itself.