The town I'm from, Eugene, Oregon, did this too.

They later reopened it, but put in roads that let cars through, but very slowly. Seems to be a good compromise.

Closing a road entirely is probably something you should do once you're at such a level of pedestrian traffic that the car lanes are impeding pedestrians, which isn't terribly common in US cities. However, making areas where people don't drive fast is absolutely a win.