This was a very cool feature of The Matrix Online before Sony Online took over development from Monolith.
At scheduled times, The GM Staff would log in as Main Story Characters and act out public Storyline Events for all the players to participate in or watch from the sidelines. Sometimes they broke out into massive NPCGM+PlayervEnviroment Fights where the Players and NPCGM's fought against huge hordes of monsters and enemies invading an area.
These events were Epic, I'd love to see some show up in XIV. Right now we have GM like NPC's show up yell at the players and cast buffs then disappear. Still pretty cool, but would love to see it bumped up a notch.