Actually, you don't need ID to walk the streets of your city. You were easily able to re-route around the small cordoned-off area.

And while I agree with you that ID-screening large numbers of people has limited security value, it doesn't have zero security value. It doesn't form an airtight seal of perfect security around the cordoned-off area, but it gives the police a chance to identify people who are using forged IDs, or who act really, really suspiciously around the police, both of which are of at least some use in reducing crime.

I would say that the usefulness of ID checks around areas that are obvious targets for criminal activity is probably not smaller than comparing such checks to Soviet-style repression.