R. Chanan Morrison, Gold from the Land of Israel: From the Writings of Rabbi Abraham Isaac HaKohen Kook, pp. 133-134 (online here):
Where would one expect that God would reveal His Torah to the Jewish people? The logical place would be on the holiest mountain in the world — Jerusalem's Mount Moriah, the site of the Akeida, Jacob's holy "gate to heaven" [Gen 28:17], the spot where both Temples stood. Why did the revelation of the Torah take place outside of the Land of Israel, in the middle of the desert?
The fact that the Torah was not given to the Jewish people in their own land, but rather in a desert, in no-man's land, is very significant. This indicates that the inner content of the Torah is relevant to all peoples. If receiving the Torah required the special holiness of the Jewish people, then the Torah should have been given in a place that reflects this holiness. Revelation on Mount Sinai attests to the Torah's universal nature.
This idea is corroborated by the Talmudic tradition that "God offered the Torah to every nation and every tongue, but none accepted it, until He came to Israel, who received it" [Avoda Zara 2b]. This Midrash is well-known, but it contains an implication that is often overlooked. How could God offer the nations something that is beyond their spiritual level? It is only because the Torah is relevant to all peoples that their refusal to accept it reflects so harshly on them.
The Torah's revelation on Mount Sinai — as a neutral location belonging to none and thus belonging to all — emphasizes the disappointment and estrangement from God that the nations brought upon themselves by rejecting the Torah and its ethical teachings. For this reason, the Sages taught that Mount Sinai "brought enmity upon the nations of the world."
In the future, however, the nations will recognize and correct this failing...