Playing a mmo with magic and coming back from the dead, and you want to talk about realism? First Collision detection isn't needed on players because griefing by making giant lines to cut off parts of the city is stupid. Or blocking people from going to a dung. I can understand mobs having it, but in general if SquareEnix were to add a system like euphoria, where your character ajust the feet so they are always on the ground and sort of making it like Assassins Creed where your character moves with the crowd not going through them but turning to the side or something would make a collision system work. At this time the game needs a more work with both net code and player pop in before they could even consider your idea or even mine.