From a Jewish Press interview with Rabbi Aaron Rakeffet-Rothkoff:
Today we all wear uniforms. What is the concept of wearing a uniform? What is chassidus all about? It’s beautiful. You have a social order, you build a wall around yourself . It’s a way of protecting yourself from outside influence. My generation didn’t need it. When we made a commitment, we made a commitment. That’s what I meant.
But if a black hat will keep you frum in America, you should wear two black hats, not just one. To me, being a Torah Jew is the most important thing in the world .
But when all is said and done, the chassidim conquered America. The Litvakim lost. In the Litvishe yeshivas no one dressed the same. When I learned in Lakewood, the only one who wore a black hat was Reb Aharon Kotler.
Even the old mashgiach, Reb Nosson Wachtfogel, wouldn’t dare wear a black hat. No one wore black pants and white shirts. It was unheard of. Everyone dressed different and stylish. In YU, not so much. Lakewood was more stylish because it’s part of Slabodka mussar [to dress in a dignified manner].
So you see the different mode of dress as a sign that chassidim have “conquered America”?
More than that. We think like them. There’s da’as Torah. Bachurim worship the ground their rosh yeshiva walks on. That didn’t exist when I grew up. When I grew up the roshei yeshiva were mortals. There was no da’as Torah. You could argue with them. But who ever argued with a chassidic rebbe?