I live in a very rural area with poor cell phone coverage. I'm happy to provide a WiFi signal for the lost people who are in front of my house trying to figure out why their GPS has led them here. We get a few each year, because Google Maps shows the road past my house going through while in reality it's closed in winter.
I also like it that I don't need to play the "what's the password" game with houseguests. I like that I don't need to input passwords to screenless devices using clumsy and slow input methods. I like the idea that the default should be sharing what you can afford to share rather than keeping everything private by except by special arrangement.
More generally, I don't think that closed networks substantially improve security and I don't like the push to require them. It's great to have the option to keep people off of your network through passwords or MAC filtering, but I don't like it being the default. I don't like technology that tries to enforce its own opinion about social norms.
Contrary to the other poster, it's not laziness. At this point it's frequently more difficult to host an open network than a password protected one. It might not be a good idea, but it's a conscious choice.