Another triumph of textualism -- well, maybe the triumph has not yet occurred but it is gaining momentum -- is in regard to how one deals with the tzitzis strings from one's tallis katan undergarment. The vast majority of halakhic authorities rule that it is proper to wear one's tzitzis strings out and visible, although allowing that it is technically permissible to tuck them in (see Shulhan Arukh, Orah Hayim 8:11 and commentaries).
However, the custom in Europe prior to the Holocaust was generally to tuck the tzitzis in. Particularly in Eastern European yeshivos, where one would have expected the most fervor in adhering to the strict letter of the law, the practice was to tuck the tzitzis in. R. Yehiel Mikhel Epstein, the rabbi of Novardok, attests to this practice in his Arukh Ha-Shulhan (Orah Hayim 8:17, 23:2), even while decrying it. The oral history from that period also attests to it. R. Nosson Kamenesky writes in his Making of a Godol (pp. 528-529, 579-580) about how visitors to the Mirrer yeshiva were suprised that the students there would not take their tzitzis out while reciting the Shema, and how that was also the practice in Slabodka. Note how they were not even surprised that the students would normally tuck their tzitzis in, only about how they kept it that way even while reciting the Shema. On Shabbos, I asked someone who learned in Hayim Berlin during the 1940s what the practice was and he said that about half of the yeshiva wore their tzitzis out, but many of them tucked them into their pockets or wrapped them around their belts (the latter was the practice of R. Hayim Soloveitchik; see Nefesh Ha-Rav, p. 105). He could not remember what R. Yitzhak Hutner did.
The reason for this practice seems to have been due to the mussar concept of dressing stylishly and respectably. Wearing one's tzitzis hanging out looks "shlumpy" and is contrary to the mussar philosophy. Since it is technically permissible, it was adopted. (My wife told me that one thing she found striking about me while we were dating was that I tucked my tzitzis in my pockets, which she thought looked dignified.*)
However, despite the seemingly impeccable pedigree of the practice, it has largely fallen out of force in the yeshivah world. This, I presume, is due to the force of textualism. The standard halakhic texts -- in particular, the Mishnah Berurah (8:26) -- oppose the practice of tucking in one's tzitzis and the oral tradition from the European yeshivos seems insufficient to counter that force. Perhaps it is the death of true mussar that has facilitated the death of this practice as well.
On the sources regarding this practice, see the article by Jason Weiner in the Spring 2005 issue of the Journal of Halacha and Contemporary Society.
* For the record, I now tuck in my tzitzis entirely.