Public place is in an existential crisis due to the technological development that is responsible for the disappearance of collective clusters which were inherent to the traditional communities.
Many contemporary ideas about public places are born out of a nostalgic feeling in which a geographically group of people expresses their bond on a social, political and economic way at these places (squares, parks). But this nostalgia is too romantic, preventing the development of ideas about public place. History shows us that there has never been public places where everybody was welcome and could participate in the social, political or economic network of a community.
Even the Greek-Roman Forum, a beloved example of great public space, was only accessible for free men. And the great 19th century parks were only accessible for the bourgeoisie.
Certain groups of people have been always excluded from these public forums. Social revolutions in the 20th century have liberated these groups and tolerance towards 'more strange' behavior in the public realm was propagandized. In addition, the growing individualization and cocooning in the 20th century (mass-consumption, pop-culture) let to the 'evacuation of the public realm' by the middle and high class. Less 'eyes on the street' (Jane Jacobs) let to a growing feeling of insecurity which let to the privatization of public place.
I think the misconception about public place is the difference between the geographically bond and the social, economic and/or political bond that people have.
1) it's not strange that the middle class gave up these public forums and that the mall would became their collective realm. There are rules of conduct and the exclusion of certain groups. Becoming a consumer instead of a civilian, is a price they are willing to pay.
2) critics who say that malls are bad because they keep shoppers away from downtowns; they change people's perception of public space into consumer space; they prevent social, economic and political intervention between people due to a lack of social, economic and political diversity, peculiar to a traditional city (nostalgia!) are not entirely right.
Then there is the increasing Disneyfication of the city due to the economic importance of mass tourism which leads to 'urban safaris'. The public realm is now a historic attraction designed to be consumed. The once excluded groups of people are excluded again.
There are no real public places, only collective places. Different types of people are excluded in these different collective places. But they are successful in their own way! And that's no coincidence.