In our parasha, Moshe is told to pass on the leadership to Yehoshua, a fine candidate to replace an irreplaceable leader (Bamidbar 27:18). The midrash illustrates the seriousness of the loss of Moshe, saying that had he brought Bnei Yisrael into Eretz Yisrael, the Beit Hamikdash would not have been destroyed and no nation would have been able to stand up to them. The author of the Mishne Lamelech asks how Moshe would have prevented destruction, considering that the nation committed the three cardinal sins.
He answers based on the p’sukim (Devarim 4: 22-23) that connect the ideas that Moshe was going to die and that Bnei Yisrael would worship false gods. He explains that with Moshe tapping into the merit of Eretz Yisrael, the desire for idol worship would have been nullified. In that way, Moshe’s entrance would have prevented the things that brought on the destruction of the Beit Hamikdash from occurring.
Rav Yisraeli z.t.l. (Harabbanut V’hamedina, pg. 310) raises another way in which Moshe’s leadership in the Land would have prevented destruction and Yehoshua’s shortcoming in this regard. Bnei Yisrael’s entry into the Land after 40 years of wandering signified a sharp transition from a life that depended on miracles to one that externally appeared natural. There was no more manna, special fire, or special cloud to show Hashem’s presence on a daily basis. The people had to fight and settle the Land. The spiritual challenge was to recognize that within the "natural" life, Divine intervention affects everything. That is why the first battle, the Battle of Jericho, included a miracle. They circled the city for seven days with the ark of the tablets; on the seventh day the walls fell to the sound of the shofar.
In order to capture the miraculous nature of the event, a ban was made on use of the city’s spoils. However, this was insufficient to train the people’s mindset. Hashem had told Yehoshua that in order to succeed, the sefer Torah would have to be with them and be studied day and night (Yehoshua 1:8). Because this imperative was not fully kept, an angel appeared and told Yehoshua that he had failed to involve himself in Torah study during off-times between battles (Megilla 3a). Rav Yisraeli said that he thus failed to put Torah at the center but had set the stage for the ultimate deterioration to the point of violating the three cardinal sins.
In contrast, Moshe was able to tell his father-in-law that he spent all day judging the people (Shemot 18:15). This was not just a matter of dispute resolution but a way to teach people that the Torah’s laws apply to every aspect of one’s life. They show the Divine wisdom’s breadth and relevance. This is a message that we, as dayanim in modern-day society, must remember. Hopefully, we can display the Torah’s beauty and significance to those who come to us for judgment.