I really think it could be done in a way that doesn't become spam talk.I love all the ideas except for the Town Criers. There's just too much room for abuse. It's bad enough I see all the other smack talk spam while trying to communicate in chat....
I myself have been running a character named Event Announcer to announce the events for several of our governors on Great Lakes. Because I know it annoys people to be spammed, I'll pick about two or three, thirty minute stretches a night during prime time where I'll have him do an event announcement every five or so minutes. So far I think it has played a large part in increasing the attendance to several of the shard's events as well as spreading the word on where to find news on upcoming events. I've even had some players from outside the governor or rp player pool ask me to announce their events. So it's clearly popular. The only drawbacks are that I of course had a jerk from a guild I wont name, but most GL people will figure, call a GM on me claiming I was impersonating a member of EA somehow by having an event announcer. The other is that unless I am around, it probably isn't done. A few people have helped with it, but it's way too player dependent.
A system where a herald shoots out a short event announcement every five or ten minutes I think would be acceptable. It wouldn't be like the random news spam from current heralds where it seems every time someone walks on screen or says something out loud it starts spamming.
You are very correct that it is a target for abuse, but the culprit would easily be found since it is limited to one person, the governor. The question is Broadsword enforcing the RoC that would of course include such abuse. It is a shame a game this old still hasn't learned you have to enforce your RoC. Almost every game since has learned it's better to lose that $10 from that one person forever than eventually $10 from twenty people forever.