And this isn’t simply true pragmatically. Philosophically as well, we started looking for movements to justify our lifestyle. The aforementioned Chassidus, Hisnagdus, Mussar, Hirschian neo-Orthodoxy were all trying to provide a basis rather than relying on Tradition, as Tevya the Milkman would have.
In distinction to Dr Soloveitchik’s thesis, I would instead speak of two ruptures. The first was the Haskalah, and with it the fall of mimeticism. However, the response to this in the 19th century was primarily to find new derakhim to give depth and meaning to our lives. (This is even true for Brisk’s hashkafah that halachah stands on its own, and hashkafah is to be played down, and the Hungarian approach of banning change. Asserting that structure must come from halakhah, or that one must manually preserve that which was hitherto part of the Jewish preconscious, are themselves textualist, formal changes.)
The Alter of Novorodok, in the first essay of Madreigas haAdam, speaks of various eras in human history. From the tanna’im until the haskalah was the period of the yeshiva. With the haskalah, the ir, the city, went out of sync with the yeshiva. Therefore there was a new need for Mussar, for the conscious inculcation of those values and reactions that until then would have been transmitted unsconsciously. In our terms, toras umasekha no longer tracked mussar avikha. It now had to relayed textually and formally, in the manner of mussar avikha.
It was therefore after the haskalah that the Ashkenazi world faced a fork in the hashkafic road, between sheleimus (self-completion, walking in G-d’s image) and deveiqus (cleaving to G-d, walking to Him).
The shift after the Holocaust was, in my opinion, the loss of direction. Rather than trying to fill in the gap with a formal philosophy or a program for tikkun hamidos and/or deveiqus, we’re just in a vacuum. We’re not just textualists, we’re focused almost exclusively on halachic texts. Aggadita is limited to nice truisms that can be repeated at the Shabbos table. And ironically that gives us fewer tools for halachic resolution. How does one decide which pesaq is right amongst those justified by the sources without focusing on a pre-halachic definition of “right”? And so we “play safe” or invoke the rules of doubt. A 19th century Chassid had a priority system by which his poseiq could decide which issues warrant chumrah, which qulah.
Uncoinicidentally, it was after WWII that Rav Dessler said we need to pursue a fusion of the two paths. That our generation is too poor to select Mussar or Chassidus (being the movements that extended sheleimus and deveiqus to their maxima) exclusively, that we need all the tools at our disposal.