UO only had this experience because there was nothing else like it, exactly. PVE and PVP players and casual and sweaty tryhard and everyone was in one world, and the game actually forced interaction between those players, often to the detriment of one party. People say they want experiences like that, but they don't. They want a walled garden that isn't too hard and will give them new shoulder pads for spending 2.5 hours grinding after work.

UO was the last MMO that made the mistake of trying to be a world for everyone to live in.