The breakdown of the family and multi-generational households has made pensions a legitimate requirement. People don't look after each other anymore. Everything has been individualized.
Even my Southern European grand-parents, who use to live in a house with like 15 people back in Europe, in their 90s now, still prefer to live on their own, even they don't want their kids or grandkids living with them. So its not even a new generation thing, people of all ages in the west want their own individual lives away from family.
Its hard for people to live with tons of other people once they experience living by themselves for a long time, you just get use to it, and don't want it any other way, you don't want to go back to living with tons of people again.