1) It seems like this would be easier to plan for people if they knew when to plan it for: I'm all about showing up to these things if only just to be counted as a number, but I can't really commmit if I don't know when it's gonna pop up (or even approx. time of day etc).
2)With any crowd large enough, I think there's always a very subtle threat of violence. I'm not maybe as nonviolent as other folks here, and so I don't necessarily see that as a bad thing. The idea is that there's massive, massive crowds, and they're gathered there specifically because they're angry. The more nonviolent they are, the more constraint they're showing, but everyone knows what it's like to be angry. It's like "Yes, this is how many people we have. And we WILL gather together in our righteous anger. We're behaving ourselves, but just imagine what we could do if we weren't."
It's not exactly drawing a line in the sand, but it does suggest that people are getting closer and closer to a more subtle line at which point we stop showing that restraint.
I'm not condoning violence, especially over something like marriage equality, but I am just kind of observing how that kind of subtle dialogue goes. I think that even if there were some way to fully remove that element from peaceful protests, they wouldn't be nearly as effective worldwide.