My fingers are numb from responding to comments on Pesachim 94! Thank you all for the stimulating ideas and thoughtful feedback, and apologies if I have not responded to every detail. OK, granted that some of you are convinced that a great many of the Rishonim were rationalists and you find this view very appealing. Here is my simple question: Why? I have a Moreh Nevuchim on my shelf that I read once upon a time, but find so much more meaning in the world view of Nefesh haChaim or the Ishbitza (just to take random as examples) that I can't understand what is driving you people. And my impression is that not just the chassidic world or yeshiva ba'alei machshava, but even the modern orthodox world (I hate using labels, but it makes it easier in this case) has a preference for the mystical over the rationalist: the Young Israel closest to me hosts a Sefas Emes shiur, another modern orthodox shul hosts a Shabbos shiur in Zohar, one of the largest and most vibrant kehilos in the 5 Towns is R' Moshe Weinberger's Aish Kodesh, and among the neighborhood yeshivos certainly Sha'ar Yashuv is known for emphasizing chassidic style "machshava" as well as traditional gemara learning. Rav Kook emphasized the need to teach the "hidden" parts of Torah to our generation, and R' Soloveitchik critiqued Moreh in part IV of his Halakhic Mind. "Mysticism" does not mean belief in witchcraft or ghosts or new age healers or thinkers -- it includes a systematic way of looking at the world and one's relationship to G-d, as explained by seforim like the Ramchal, Maharal, Nefesh haChaim, Tanya, and others. What is so unappealing about these works?
To flip the question around: why reject rationalism? A few reasons off the top of my head:
1) Its explanations are not convincing -- do you think eating non-kosher is unhealthy? (Ramban VaYikra 11:13 cites the scientists to support this!) I can't have no way to know what is good or bad for my soul, but I can empirically test what is good for my body.
2) It makes religion the handmaiden to other values -- mitzvos are measured as "good" relative to other values (e.g. health, moral refinement, "justice") instead of being appreciated for their intrinsic worth.
3) Much in life seems mysterious and to defy rational explanation, and religion is no exception. The poet or painter speaks to us about deep human truths that the scientist or philosopher cannot capture or articulate.
4) Reducing Torah to a means toward moral or intellectual perfection alone robs it of its distinction from disciplines like law, philosophy, etc. which also stake a claim to these same goals.
5) Laws such as chukim are by definition inexplicable and point to a need for subservience to G-d without external justification - i.e. "because He said so".
This is not an exhaustive list, but a starting point. I'm not so much interested in responses to these critiques as much as an explanation from those who have both sampled Moreh Nevuchim or Ralbag or some other rationalist Rishon and also dabbled in the world of R' Tzadok and Maharal: Why does the former grab you and not the latter?