Imagine how much innovation there would be in NYC if it were blanketed in free wifi? (not to mention it would make living here even more amazing) Free wifi doesn't need to be a pipe dream, and "always on" broadband doesn't have be limited to expensive 4G.
NYC could create incentives for property owners to provide free wifi. Similar policies exist for non-tech public goods - for example new property developments are required to have public use space. The city doesn't build the network. It just provides incentives, so the program won't cost taxpayers much.