Interconnected had
something to say on the subject of lessening social contact and the fact that nobody knows the people living next door any more.
I think it's fairly simple - I don't need to be very social, so I'm not. If you're self sufficient, then you don't need to form more than perfunctory bonds with those around you. This is, of course, more true in cities, where all of your needs are commoditised rather than in less urban environments, where you have to actually interact with the provider of your needs.
Also, in ye olden days I'd only have those people around me to be social with. Nowadays my social circle is largely composed of people I'm unlikely to meet, due to the internet. This is fantastic in some ways (I'd never normally be able to meet people with interests like that) and terrible in others( I'm not making social contact with those around me).