The Gemara (Nedarim 38a) states that the Divine Spirit only rests on a person who is powerful, wealthy, wise, and humble. Now, we can appreciate the importance of wisdom and humility in a prophet, but why does he have to be powerful and wealthy?
Rambam explains this with a principle discussed in the Mishnah in Pirkei Avos, which states, “Who is mighty? He that subdues his evil inclination. Who is wealthy? He that is satisfied with his lot.” The power and wealth spoken of are internal, spiritual attributes, rather than brute strength and heaps of money. However, this explanation does not appear to be the straightforward meaning of the Talmud’s list of requirements, since the Gemara proves these requirements from cases of prophets who were actually rich and strong. (I am aware of alternate explanations of these proofs, which I discuss in the chapter on giants in Sacred Monsters, but they are not straightforward.)
There is another answer. One of my favorite childhood books was Richard Adam’s best-selling story about life in a rabbit warren, entitled Watership Down. The rabbit Fiver, a small, weak and pathetic bunny, also happens to possess the power of prophecy (admittedly unusual in a rabbit). Fiver experiences a vision that the warren is about to be destroyed by developers, and desperately tries to persuade the other rabbits in the warren to leave. But the other rabbits simple don’t believe him, and who can blame them? This pathetic and sickly little rabbit is obviously delirious, deranged, deeply disturbed, and desperate for attention.
Rabbi Samson Raphael Hirsch explains that anyone who is sick, or poor, or generally pathetic would lack credibility as a prophet. Perhaps he’s pretending to do it out of insanity or to gain attention – after all, he’s got nothing to lose. The requirement for a prophet to be healthy and wealthy is simply to ensure that people take him seriously as a man of stature.
A similar reason applies to the laws of appointing a king. Rambam rules that one may not appoint a butcher, hairdresser, bathhouse attendant or suchlike as a king. This is not because such people are innately unsuitable for the task; Judaism cares more for internal qualities than superficial prestige. However, since the work of such people is not prestigious, the public will not take them seriously and their authority will be compromised. The requirement is based on a pragmatic outlook, rather than being an attestation to the importance of a high-powered career.
There is a common perception, with much evidence to support it, that the rabbinic leadership in the charedi world suffers from such weakness. I have long wondered whether this problem might stem from the medical innovations of the modern era. For most of history, the only people to survive to adulthood were those of a strong constitution. Very few people reached old age; those who did were people of immense strength. And the authoritative rabbinic figures of fame were often younger than we assume. When Ramban stepped in to the Maimonidean controversy, he was only in his thirties! Today, on the other hand, many people survive to their eighties and beyond, and (perhaps as a result) "Gedolim" usually do not receive this title much before that. On many occasions, this means a decline in mental aptitude. But even if they are mentally acute (as Rav Elyashiv seems to be, at least until very recently), they are often weaker and more subject to manipulation by askanim.
It turns out that I was not the only person to reach this conclusion. There is a fascinating new article, "The leadership vacuum facing ultra-Orthodox Jewry," which makes this point and several important other points. It's an absolute must-read. You can read it at Ha'aretz, or you can read it at Vos Iz Neias and see the mixed reactions of charedi readers.