I know quite a few people who lived in NYC during the time. Economic conditions were fine then, yet the areas weren't. Most know exactly what happened and how. The park next to the Stuyvesant, UES, Hells Kitchen, Union Square, none were places where you wanted to be out late at night or could find prostitutes and drugs everywhere. Now you find people using wifi.
One of my coworkers, who grew up in a rough section of Brooklyn, directly attributes several run-ins with the NYPD when he was jumping the subway, among other small things, as one reason for him not getting into more major trouble.
Police appearance, as well as cutting down on petty crime, created a much better atmosphere. Much of that was also driven by local police command vans which were placed in the worst areas, keeping an NYPD presence at all times.
Bringing the dregs in and allowing petty crime is the way to allow worse crimes.