You make a good argument, Dolly, but unfortunately you're comparing apples to oranges.
Building your Wi-Fi network without any firewalls or security layers (such as WEP) despite the fact that they are built into installation is more akin to building a house and making the provision (cut-outs) for doors and windows, but not installing them - instead leaving them wide open for all the world to see. The provisions are there, but you chose to ignore them - despite security warnings.
That being said, I'm not saying it's ethical to harness another's Wi-Fi connection, but if you don't take those (easy) precautions, it's an open invitation to those with looser ethics.
I live out in the country, where the majority of my neighbours are either too far away to receive my signal or they don't use computers. Despite that fact, I have my Wi-Fi network installed with 128bit security. For people just like the original poster referenced. The ones who might stop their car in front of my house and 'hook up'. I'm not worried about them using my internet connection - it's unlimited broadband - I'm more worried about the malicious ones looking for more. If my internet was a pay-per-use system, I would likely be even more vigilant.
Just my 2¢