Toggled ability to have the actor's name show up differently to players (in color, font, or shape), In-server simulpresence (maybe on repeater TV screens in every tavern in the land), and robust scripting for the actor to deliver prepared speeches are logical next steps to this.
These tools alone make Meet and Greets and Hear Me, Zion events viable - instead of needing a team of actors to try and cover every server, one employee can implement these events and get many more eyeballs on his performance than previously possible.
The random and capricious nature of events and the real danger of flash crowds ruining the game experience are still in play - how do you get good penetration amongst your player base without having events that cause players to gather and crash the server?
The answer here is triggered eventing. This sort of scheme involves the placement of invisible triggers throughout the gameworld with common designations - "Live Events A", "Live Events B", etc. The common "Oh no, bad guys" event can be presented to players, and all Live Events A triggers are turned on. Players who move into these areas (which will become learned, I'm sure) will see event creatures spawn when the players move into proximity. These creatures, however, are displayed client-side for the player (and his group) and provide a singular experience for a group of players, much like an open-world instance. While this doesn't help keep players from gathering, having designated locations (and multiples of these throughout the game world) can keep players spreading out a bit. Good event design plays in here, by asking players to progress from one spawn area to another, cleaning up crowded areas as the earlier arrivals move to the "B" and "C" spawn areas.
Which leads to my second-to-last suggestion for this article, the Guided Experience. In this event type, the Live Events team member uses simulpresence, triggered eventing, and a pre-made stock blend of monsters, text, lore, and rewards to "mix and match" an event for a lucky group of players. With proper automation (invisible triggers, prepared speeches, pre-made creatures, etc) an LET member can solicit a small group of players (on every server at once!), drop the triggers needed, and walk away until a time limit or signal is given to end the event. The LET member pops back in, provides an outro to the experience (or drops in at checkpoints for more ambitious versions of this plan), and rewards the players. A personal touch and a robust adventure - breaking that mold of quest givers standing stiffly in their houses, at a tiny fraction of the cost of previous efforts at live events. The beauty of this is given enough monsters, text, etc, the eventer can quickly whip up something good, give it to some players, and repeat in much less time than in current live events systems which involves a lot of typing to make one little thing happen. "Run Event 32, Reward 4, and Monsters 6B" would be the level of planning needed here. The actor is freed to do more acting and less typing in of commands to make the event happen.
To all of this, I would add one new game feature - the gathering place. Every MMO has at any given time around a sixth to a fifth of their players standing around socializing and generally hanging out. Providing interesting locations to do this is often an under-estimated part of MMOs. Players in an MMO beta will often find their own locations to gather and socialize. By personal experience I can tell you that more often than not, that location is for one reason or another a very poor gathering place in terms of server health. Unfortunately, before this can be properly assessed, the beta players have already taught their successors and the broader playing public these socialization locations - to the overall detriment to the game.
Starting early with an interesting gathering place is important, I feel, to live events. Establish your downtime locations - make them fun and interesting places to stay for players who are not adventuring, and then you reinforce these designated locations - your LET members will look in these places first for downtime players to approach with the offer of an event. Once players learn that events are to be had in these locations, you have now built a dual-experience paradigm for your players: go out into the world and adventure, or socialize and perhaps adventure will come to you. Remember, these players are already taking downtime, but now there is a chance for a shot of adrenaline, a chance for a shot at a new experience aside from the normal questing and dungeons you find in the greater world.
I firmly believe in Live Events - I believe that every player hit by a well-made event is that much more a fan of your game. Disney, the original theme park, learned early on that having only rides and occasional shows does not make for a truly magical experience - it takes the spontaneity of a human actor to make a visit that much more meaningful. This is also true, I believe, for MMOs.