Not a bad idea, but events take time, preparation, etc. those you are refering to were done by GM-Ayu who was really into those kinds of events, they were really fun. Spawning monsters in some town isn't too hard, but the current nobility and allegiance mob would need to reworked first as their drops are too much, they were made for a 1 time thing with a large group.
About Nobility we have an update coming, not sure when but it's done scripting just needs testing. A dungeon is not in the plans for now as we already have a custom dungeon in the work.
