Why is fireworks watching so micromanaged here?

This is partially a rant, but why is it that when there's a big fireworks event, all of the best places to watch fireworks become off limits? Rooftop gardens, bridges, plazas with open views, higher floors of buildings–it's like they're trying to create overcrowding in the few areas you're allowed to watch. If they just had extra crowd control near the trains but otherwise left everything open as normal it would probably help spread out crowds significantly. I just don't get it.

by mustacheofquestions