I think that public spaces are a great thing, and I'd be happy to see them make a comeback. During my (brief) time in Europe, it was incredible to go to a store, pick a cafe and just sit outside with friends while there's a lot of other people doing the same thing. In this case, it's probably a difference in city planning that enables it to happen in Europe as opposed to America.
That said, it's still possible to create these areas. I feel that they (should) promote community, support local businesses, and also promote activity. If you do it right you should have multiple public areas within walking distance of each others.