The dress thing is just a classic social psychology issue. For a community to stick together they need some distinct dress. It's actually written into the Code of Jewish Law that a Jew is supposed to dress differently from those around him. Every once in a while in history, for whatever reason, that falls apart--and then starts up again. So the dress gets fixed at that "healing of crisis" point.
Now, if you'll allow me to make a small comment: I notice you are asking questions about very external matters--the things you see, but don't really count. Proof that it's external: A person can wear all the right clothes, and be sinking terribly on the inside.
But don't you have any questions on what these people believe? What drives them? Why are they still around? I mean, about the engine under the hood.
Rabbi Tzvi Freeman for Chabad.org