People think that's how it was in the past, but in fact it's not, there's quite a bit of research on how people were more pro-social, even a couple of generations back, say the generation that went through the war. One of the fairly obvious reasons is that without a well-developed state, your very survival might depend on others, and certainly any care. People also went to Church which takes all comers and although there were many disadvantages to this, there was also the advantage of people being included who otherwise would be left out of society. The classic text on this is 'Bowling Alone' by Robert Puttnam. Basically going to bowling leagues, being in groups with friends and being out and about creates social capital that is better for our health than doing things individually or always as a tight family unit for pretty obvious reasons.
I don't think it matters if any one individual has a more introverted life, no need to go around in big groups if you don't like, but it is absolutely worth chatting with neighbours, the people down the shop, wider circle of aquaintances and having if possible one or two friends.
The point about social skills is very interesting, I made my children ask in shops and restaurants for anything they wanted from a very early age- if you don't look at the person, ask politely for an ice-cream, then you don't get one, same ordering food, same chatting for two minutes with visitors. Look them in the eye, say hi, ask a question, then they were free. I think these are skills that have to be encouraged and definitely before the teen years when that awkwardness sets in. It's even more the case in families with ND like ours where without explicit training, these things may not be picked up from casual interactions. I feel I can go anywhere and chat, even if I feel nervous or don't fit in immediately, and that is a huge benefit in my profession now as well.