An often overlooked reason for people acting stricter in ritual matters is the increase in Talmudic learning. When one learns a new opinion and spends days analyzing and justifying it, there is a natural tendency to incorporate that view into one's behavior. Refraining from doing so could lead to a dissonance between one's study and one's practice, something that seems inauthentic. While a strong backing in the study of practical halakhah could avoid this, because one becomes comfortable with following only one (or a few) opinions of many, this is not always the case and, regardless, the current environment of Talmud study does not include much in-depth study of halakhah.
A similar idea is pointed out by R. David Horwitz in his 1982 review of R. Moshe Sternbuch's Mo'adim U-Zemanim ("R. Moshe Sternbuch's Halakhic Novellae" in Tradition 20:3 , p. 266):
One of the salient features of Mo'adim U'zmanim, and one of which the author is quite proud, is the frequency of humrot (stringent rulings) that arise from the examination of a variety of halakhic issues. R. Sternbuch does not advocate practicing humrot that have no halakhic basis or that would entail other halakhic problems. Nor is his approach and advocacy of humrot as a "defensive measure," that is, either due to the ever-deteriorating spiritual position of the Jews, as the Shlah maintained, or as part and parcel of a personal mussar doctrine, as R. Moshe Hayim Luzatto suggested. And it is not a device to prevent assimilation into the general culture by increasing the regimen of the Halakhah. R. Sternbuch's position (one that is not a solitary view either) requires that the attempt to fulfill all the mitsvot with precision be combined with any fresh results from inquiry as to the nature of certain mitsvot. Thus the halakhic constraints of new theoretical possibilities must be accepted as practice.R. Horwitz's point is more about acting strictly based on a new (conceptual) understanding of the law, but I believe that it also includes conceptual understandings of minority opinions that one would otherwise not follow. His idea does not stem from a lack of familiarity with the halakhic process, but merely new insights into the accepted rulings that leads to further practices. The idea I am adding is that often students will put into practice something they have learned, even if it was intended only as a theoretical study of a non-normative position.