There are different kinds of not-frum and different eras as well. I suspect, for instance, that many BT’s from 60’s era parents get along well with them because for 60’s era parents Yiddishkeit is just another alternative lifestyle.
My parents and their friends are of the post-immigrant assimilationist generation for whom being “Jew-ish” was a neurosis that they could not shake either by becoming completely not Jewish (not possible) or by accepting Torah. They had no values whatsoever except to find the path of least resistance. As bad as the 60’s were and as bad as the times of the Bundists and other misguided Jews were, at least those people lived for something more than themselves and did not just want to take the easiest way out.
When I look back at history, I see how little my parents’ generation achieved and how slowly things happened during their peak years. Everything we take for granted today, except perhaps air conditioning, was for the most part invented before their birth or in the past 20-30 years. Most of the medications that really make a difference in people’s lives, like the new cardiac drugs, better antibiotics and immunological drugs, are newer inventions. The Internet – of course it was invented by Al Gore but those of us who know better know it started to become practical in the 90’s. As a teenager I took pictures on the same old basic film Eastman invented, just updated with a few twists, and I developed it myself in the same old smelly, dangerous developing solutions that were around in 1920. Now we have digital. Computers – how old is Steve Jobs?
They sought only stability and theirs was a vapid not really Jewish but not really goyish culture. Their ways are dead; a few of their descendants did do tshuva but most are part of the New Age mishmosh and don’t identify as Jews.
Maybe it was beyond their control because they were children during the Depression and WW2, but most of that generation of secular people from the US has little to teach us, and the secular Jews of that era are the second son, not the fifth son of the Lubavitcher Rebbe ZYA’s teachings. When Reb Aron Teitelbaum of Satmar said American Jews are not under the category of tinok shenishba, I was shocked at first, but then I realized I would say the same about my parents’ generation, who could have stood as proud Jews but instead chose non-Jewish, yet non-gentile mediocracy that reduced Judaism to a few pejorative Yiddish expressions and a few abridged yomim tovim observances. (Those who are the same age and survived the Nazis, Communists or the upheavals in North Africa and the Middle East and remained true to Judaism are of course heroes.)