This article makes some good, critical points about hotspots in McDonald's: In Australia, the fee to use the Wi-Fi connection is more expensive than many items on the menu. A lot of people eat at McDonald's because it's cheap so it's reasonable to wonder why those same people would pay for an expensive Internet connection.
McDonald's has been aggressively building out hotspots around the globe. We wrote recently about an article describing McDonald's forward thinking use of technology, including the wireless networks, to make workers more productive and cut costs on telecom services used by workers. Perhaps McDonald's main goal in rolling out Wi-Fi is for workers, not necessarily to earn from customers using the network. If that's the case, they might as well offer it free with a purchase because it would probably draw more business people into the restaurants than the fee-based services.