The article is also bung. The blog post, that is. Using your neighbour's WiFi is stealing, every single one of the vast array of arguments the blogger puts forward is either shallow, misdirected, based on false assumptions, predicated on absurd analogy, plain stupid, or some combination thereof.
If you're on a WiFi that you don't have reasonable grounds to conclude was intended by the owner to be free, then it is stealing. End of story. Now, can we stop it with the absurd excuses? It's even more disingenuous than the proposition that copying movies is not stealing. It is, people just do it anyway. Let's stop retroactively justifying ourselves.
Using your neighbor's wifi without permission would be unauthorized access, which is a completely different crime than stealing. Copying movies is also a far cry from stealing. The crime you're thinking of there is called copyright infringement, and it has far more severe consequences than simple theft. People who are caught copying a movie illegally only wish they were punished as lightly as someone caught stealing a DVD from a shop.
It sounds like you might have some misguided assumptions about open wifi networks. IIRC, in the early days of wifi that was one of the proposed long-term benefits of this new wireless technology. The idea that eventually open wifi access points would be so commonplace that people would have free convenient access to the internet while away from home.
If an AP is broadcasting itself as being open, and the DHCP server is granting IP addresses to anyone who requests one, then what would indicate that the owner does not want them using it? The average non-technical user might not even realize that they connected to it, since some operating systems will automatically connect to open access points by default. I've met many non-technical people who admit to leaving the default settings on their AP with the intention of allowing others to use it for free. So, while a default SSID may be a sign that the owner hasn't bothered to completely configure the AP, it does not mean that the owner had no intention to share it with the public. If someone has an open AP and is granting IPs to anyone who requests them, but they really don't want anyone else to use it, then it's clearly a misconfiguration issue on their end that needs to be corrected. Similar to someone who uploads files to an indexed directory on their publicly accessible website, but doesn't want anyone else to download them. The appropriate way to handle situations like those is to politely inform the owner of the mistake, rather than outlaw a completely legitimate use of the technology.
There's nothing wrong with making use of an open access point. That's what they are intended for, to provide convenient internet access to the public. Of course, taking advantage of the owner's generosity by using it for P2P file sharing, or anything else that would cause a disproportional load on the network, is definitely a dick move and some people may need to be made aware of that.