What really ended it was all the FUD from the cable modem companies about "Terrorists and Child Pr0n0graphers are going to Steal Your Access and you'll get blamed and Go To Jailz!", which was really about "Don't share service with your neighbor - that would mean some of you wouldn't be paying US!" It was before most of them had adopted the annoying Australian meme about putting usage quotas on service, but they still hadn't totally relaxed from the "one cable/DSL modem, one computer" model that got abandoned when everybody had routers that did NAT and anybody with kids had multiple computers active (typically new one for the parents, old one for the kids, before gaming reversed that order.)
It's also changes in customer router equipment. In my apartment complex, I can typically see 6-10 Wifi signals, and back when we had 802.11b, they were almost all open, with 802.11g half of them were closed, and now that everybody's got 802.11n, they're all closed. (And 802.11n was loud enough that once a couple of people got it, everybody else needed to use it to get a consistent signal :-) I used to keep mine open as a guest account (even after the one time that my neighbor's work laptop got virused and used my wifi to send half a million spams, which my ISP blocked and gave me a phone call about. I closed it for a couple of days until she got her virus fixed.)
I also used my neighbors' access every year or two if my DSL was down, and when I was travelling, I used the free mobile Wifi access provider "Linksys". :-)
Unfortunately, the Wifi security model doesn't give you a way to do encryption without also blocking access, which may make sense in a corporate environment but typically doesn't for home users.