Well...they needed a much bigger audience, that's all. Now just figger how much more effective it would have seemed if the mainstream media had advertised it as an upcoming event for about a week...and it had been held in Madison Square Garden on live nationwide TV with an audience of 150,000 screaming war protestors waving signs and chanting "NO MORE WARS! NO MORE WARS!"
You can do that kind of thing right when you've got the right connections.