Earlier quoted context omitted.
FWIW, I believe the idea is to segment the network so you are sharing your bandwidth, but not your "home network." A closer analogy would be letting strangers use the outhouse on your property, but not letting them in the house. The router used by Numericable here in France offers a "guest WiFi" connection out of the box. It is not enabled by default, mind you, but it is available nonetheless.
The routers used by SFR/Neuf and Free have the "guest wifi" on by default. There's even a partnership between SFR/Neuf and Fon.
Because it is my understanding from reading the EFF page that they want the Starbucks model (open network and gratis connectivity), which differs from my experience with SFR/Orange/Neuf etc which are revenue-sharing deals [in my experience].
Even Netgear(? or perhaps D-link) in the US shipped access points with some kind of silly revenue-sharing situation.