It's a shift of responsibility from the motorist to the pedestrians. The car "belongs" in the street and the pedestrian doesn't. Cars are not required to look out for people, people have to look out for cars. That's a change that shifts the generally understood purpose of the whole infrastructure.

If you and I are walking on the sidewalk, we're equals. It's as much your responsibility not to run into me as it is my responsibility to run into you. According to the article, before cars the situation was the same in the street. Everyone was equal. With the advent of jaywalking laws, suddenly cars are prioritized above all other traffic. If a car hits someone who wasn't in the street at a designated spot, the car has no responsibility for the accident.