Nice list. Loved UO, was absolutely hilarious when Lord British was murdered. Was also sad to see Earth and Beyond go away, I enjoyed the actual gameplay more than the majority of MMOGs of its time.

Other defining moments of MMOG for me: Playing one of the first 3D MMORPGs, Meridian 59. It was a lesson in how a company can kill off its own subscription-based MMO: daily play charges. When they changed the pricing structure, this game cost $30/month if you were to play every day.

Also, the first time I learned I could escape the tyranny of "official servers" with private emulated servers.