@Michel,
In traditional circles, it was understood that certain topics are only useful to those who are equipped for them by virtue of attitude, aptitude and motivation. Many of the esoteric schools have been limited to initiates because the knowledge itself requires certain pre-requisites and in traditional settings, ritual purity and observance of the normative ethical codes. (The term 'Upanisad' means 'sitting at the feet' or 'sitting up close'.) In the case of esoteric or symbolic knowledge, it was thought that if such knowledge is misinterpreted or misapplied, those pursuing it can miss the mark by a very wide margin indeed. (It was also often the case in traditional societies that certain kinds of teachings were actually politically proscribed, much as the Falun Dafa have become in Communist China, due to ecclesiastical politics and the like.)
There are many examples of the missappropriation, misuse or misunderstanding of esoteric knowledge systems in this century, for example, various guru scandals, lawsuits over the ownership of the 'intellectual property' of Yoga in the US, ongoing litigation sourrounding the well-known Hollywood celebrity pseudo-religion (I dare not name it). The fact is that, consciously or otherwise, people are fascinated by metaphysics, or maybe just by mystery, or intrigue, or thinking that there is A Secret, and they might get to know it and find eternal bliss, or at least, a lot of whatever it is they want.
So for every person who really might be able to tackle the real questions of metaphysic, it is a fair bet there will be many others who take it the wrong way, basically because of 'what is in it for me'. I would think the first and foremost traditional virtue required in the pursuit of such an understanding would actually be 'disinterest', in the sense of a motivation beyond the purely personal. However none of this sits particularly well with modernism, because it is basically somewhat undemocratic in its implications. It seems elitist, and may indeed be. For a reason. Anyway, that is my take of what the old sages, such as Miamonedes, (with whom, I might add, I am not overly familiar) might have been on about.
---------- Post added 11-16-2009 at 09:40 PM ----------
I should add, I rather like the idea that metaphysical knowledge is actually hard to get, that it requires a kind of trial, and a kind of sacrifice. It might sound a bit eccentric, but then, knowledge of how to play the piano also takes a lot of effort and sacrifice, and at the end of it, you have a new skill. The analogy is not exact, however, because in metaphysics, one is to some extent the subject of the discipline. On the other hand, it is a subject where it is possible to know the arguments without really grasping the import, and indeed one might argue that this is very much what metaphysics had become, and why it has been abandoned in so many places.