I can imaging when MLK gave his “I Have a Dream” speech, the traffic had to be horrible....I don’t think you saw the press complaining about it.
It’s important to have the right kind of people exercising their free-speech rights. Otherwise, the wrong kind of people say stuff.
Oh, maybe ... the civil rights movement wasn’t universally popular in those days. And then, as now, much of the media was in the (segregationist) Democrats’ pocket.
The BIG gatherings, from MLK in ‘63 to the annual Rolling Thunder, to the ‘09 Tea Party or Beck events have been on a weekend and/or holiday.
Today is a workday in a large city where traffic is horrendous without any outside help. I fear folks are losing sight of DC’s actually being a working city, beyond the Capitol, the Mall, monuments, etc.