Few years later, I finally get my 56kbps modem and spent decade playing the game on so many different unofficial servers as well as being GM and developer of few more shards.
I would say that UO was Minecraft of our generation: especially on unofficial RP servers you had awesome game systems scripted by community as well as sandboxed world where you can do basically anything. During my stint in game I was beggar joking around other players, owned farm, baked my own bread and make beer, been drunken sailor as well as competitive PvM warrior.
It is "real" world, that tends to create nice community of players, some like to chat, some like to joke around, some hunt dragons and another are just pure evil killing noob players, stealing everything they own and then troll them till they cry and leave the game forever.
Try that in your "bring-me-ten-wolf-teeth" click grind MMO game.