it doesn't change anything, but it makes people aware of the cause to some degree or aware of the organization... and maybe that's a stepping stone to whatever goals hey have.
but just cause their cause exists doesn't mean they will necessarily succeed anyways. there are at least half a dozen people on these forums that know of this movement since their tenting demonstration or whatever. i can say i didn't know about it prior to whole tenting action. even more if you include the global exposure. another reason why they choose to do it in the middle of downtown. coz there's a lot of people there and that means more exposure.
they could probably put out a national ad campaign too, but this is "free" exposure.