I definitely think that sp's belong in society. I have no trouble fitting in, I just use my spness to my advantage. For example, if I'm really into something, I can easily keep going for a long time and I'm not afraid to get my hands dirty. This actually helps me get along with others really well (and get a laugh too).
But I'm good at mingling with all kinds, so ... on good days I'm doing well.
Of course, because I am bipolar (j/k), I don't always feel as if I do well. But that's just my silly confidence issues.
It's just that, well, sometimes it's good to know where you feel better and where you feel less comfy about things, eventually. from experience I've seen I like some people more than others. I guess you can all relate I hope this post was useful.
To answer your question: I'm not sure it's a generation thing, but I think maybe you're talking about Acceptance and Ways of thinking, related to times.
For instance, nowadays people seem to be more accepting and open minded about certain aspects In General, which may come across as being J or not, but I don't think that's really related. It's still a personality thing. But who knows. Maybe there used to be more J's around. Maybe not. Maybe P's used to be outnumbered. Maybe ... blabla! lol that last stuff was bull