R. Yosef Dov Soloveitchik said
I will tell you frankly, the American ben torah has achieved great heights on an intellectual level. However, experientially he is simply immature. When it comes to Jewish religious experience, people of thirty or even forty years of age are immature. They act like children and experience religion like children. As a result, Jewish youth is inclined and very disposed to accept extremist views. They do this to such an extent that my own students examine my zizit to see whether they are long enough! [Laughter] The youth is extremely pious, but also very inconsiderate. Sometimes they drive matters to absurdity. Why? Because they have no experience. Their experience is very childish, simply infantile. When it comes to experiencing the emotional component of religion, boys who are really learned simply act like children. This is why they accept all types of fanaticism and superstition. Sometimes, they are even ready to do things which border on the immoral. They lack the experiential component of religion, and simply subsitute obscurantism for it. I have never seen such obscurantism as I see among some of my students today. After all, I come from the ghetto. Yet I have never seen such naive and uncritical commitment to people and to ideas as I see in America. This is the main problem we have today.
R. Soloveitchik's son-in-law, R. A. Lichtenstein remarked that
In a moment of striking candor; when my colleague Rav Yehuda Amital first visited these shores almost twenty years ago (that is, around the same time the above remarks were made, in 1974, ed.) the Rav commented to him: "You know, I have devoted talmidim....If I were to announce a shiur at two o'clock in the morning, they would come en bloc. And yet, deep in their hears they think I'm an apikoros." The remark was laced with characteristic humor and confined, presumably, to a select group. Nevertheless, it gave vent to a genuine, if painful, sentiment.The Rav, Vol. II, pp. 238-241