The thing you described about events occurring out-of-view reminds me of the "Radiant AI" system which Bethesda promised, and greatly underdelivered, for The Elder Scrolls IV: Oblivion. Allegedly the game was going to be full of NPCs with their own wants and needs, and they would take actions to fulfill those wants and needs regardless of whether or not the player was even watching. It sounds like it would lead to a very interesting world, but in practice it led to criminal NPCs being dead before the player can meet them. (The truth to this story is debated: https://blog.paavo.me/radiant-ai/)
Likewise, the concept of an MMO where you aren't necessarily safe from other players in a town sounds interesting, especially in a game with a relatively small community. Applied at scale to something like World of Warcraft, I think that it would either be penalized so heavily that no one would do it, or not heavily enough so that new players have difficulty getting anywhere in the game because they are murdered by high-level trolls as soon as they log in.