A voice from Heaven proclaimed, "There is one among you who is deserving of the Divine spirit, but his generation is not deserving of it" (Shir HaShirim Rabbah 8:11).
We often complain that we lack personalities as great as the leaders of previous generations. We may prefer not to realize that the opposite may also be true: that leaders cannot be totally disproportionate to their generation, and that if we do not have the caliber of leaders of previous generations, the fault may well be our own.
The Talmud tells us that even Moses was demoted when the Israelites sinned, because his greatness was in part for their sake, because they depended on him (Berachos 32a). The Baal Shem Tov explained that a leader is like someone who can reach a high place only because he is standing on the shoulders of others. Even the great Moses owed part of his greatness to the people to whom he was devoted.
Sometimes people who could be outstanding leaders never fulfill their potential because no one wishes to receive their message and be guided by them. Just as a nursing mother will soon lose her supply of milk if the infant refuses to nurse, so can the potential of great leaders be stifled if no one will accept their teachings. On the other hand, when people demand that their leaders teach them, the leaders must rise to the occasion, and thereby they gain in stature.
On a very practical level, the rabbi whose congregation demands frequent classes in Torah will learn and grow more, while one whose congregation is more than satisfied with sermons will not be stimulated to further study.