Shopping centers are very big business, and most of them are financed and developed not locally but from afar, by big lenders such as insurance companies. Those big investors explicitly favored big chain stores like Sears or Montgomery Ward. A big chain could pay back the loan even if that particular shopping center went belly-up. Shopping centers thus helped tilt the balance from hometown merchants to national corporations. That had been going on since at least the turn of the century to some extent, but accelerated depreciation tilted the balance definitively.
Public life is different, as well.
People come together where they shop, and malls have changed the way we experience society. In the small town that I grew up in, there are places set aside in the downtown where folks naturally come together. The courthouse lawn is ours. Anyone can speak. That's a very old tradition in Western civilization.