plus to all you wrote is the concept that people were there FOR freedom, not necessarily against anything (except lack of freedom). That's very general, and wrong when you get to specifics, but it is more empowering and cohesive to come together FOR something, rather than just AGAINST something.Imagine counter-protesting against freedom. Imagine what kind of person you'd have to be.
Oh. THAT kind of person.
At a strategic level, having rallies without a clearly defined purpose makes a kind of sense. The point is not to to complain about one specific issue - that presupposes that the regime is legitimate, is seen as legitimate, and is open to changing specific policies on the basis of popular discontent. It says 'we think you're all basically good guys, but you're misguided on this one particular thing and we're hoping we can change your mind.'
As we all know, that isn't the case. The regime is not legitimate, and it has precisely no intention of listening to the people on any matter. We can yell ourselves hoarse and they'll just wait until we go home and then continue doing what they were going to do regardless. Or maybe they'll send in the storm troopers to bust some heads.
On the other hand, a rally with no clear message sends the implicit message that, we don't think you're legitimate, and we're here to make sure you know that. This is deeply unsettling to the pathocrats. That's especially the case if the ralliers avoid giving any excuse for a police crackdown - it puts the psychopaths in an awkward position, where they really WANT to shut down the rally as its very existence is a threat, but if they do so they'll erode their legitimacy even further by attacking peaceful people who are just kind of there, smiling and having a good time.