[ptaipale]

You are thinking of Caves of Steel and its follow-up novels. The "spacer" worlds were extremely sparsely populated, just a few thousand people per planet, and the people did not want to meet physically for fear of infections and dirt (much of which was mental).

But in these novels, the Earth was living in huge underground cities; big, noisy and somewhat dirty. The funny thing is that in Asimov's future Earth, population density was very extreme, people did have very little privacy (their apartments didn't even have own bathrooms, regular citizens used only public bathrooms and toilets). This was for 8 billion people, which in early 1950's looked like a huge population. This was supposedly achieved by megacities covering entire continents.

But today, the world has 7 billion people, and will have 8 billion people in a couple of decades - and life will not be that much different from what it is right now.