Well considering the 2000 years of exile and oppression that culminated in the Holocaust, I think a religious revival would be almost expected. In my opinion the only reason there wasn't was because of Herzl and the secular Zionists, but in the the last 19th century the majority of Jews were simple (by which I mean poor and agrarian) and devoutly religious.
It doesn't matter what the majority is. Nationalism is never about the majority of the population. It's about the majority of the urban middle class, and among European Jewry, it was decidedly secular.
Zionism was ultimately a movement of Westernization. It was the culmination of assimilation of Jews to European values. In Early Modern Britain and the Netherlands, and in the 19c in the rest of Western Europe, the Jews learned to become more like their neighbors. The rise in anti-Semitism starting in the 1870s did not halt this trend, but on the contrary continued it in a new direction: Jews would become like the Europeans by founding a nation-state like the ones the Europeans had. The revival of Hebrew was not a turn away from European values, but rather a turn toward them: one nation, one state, one language. Early-20c Zionists constantly compared their fledgling nation to a pan-European yardstick, and wanted Tel Aviv, Haifa, and Jerusalem to be like the major European cities.
This means that we should look at Zionism through the same lens as reform movements in non-European areas that were deeply affected by Europe: Meiji Japan, the May Fourth Movement in China, Ataturk's reforms in Turkey, postcolonialism in former colonies. The direction of all three named movements was a rejection of traditionalism and assimilation of European knowledge, and in China and Turkey it was also accompanied by overt secularization. In Japan, the emperor remained nominally supreme, but the autocracy of the shogun was replaced with democratically-elected prime ministers, and overusing imperial edicts was considered to cheapen the post of the emperor when one prime minister resorted to them too much.
Expecting Zionism to advocate a monarchy or a theocracy makes the same amount of sense as expecting late-19c Japan to advocate a return to the shogunate.
Of note, we do see some romantic religious revivals today, of which the most common in the news is ISIS... but this is in response to the failure of secularism. The Arab world first developed Baathism, a secular modernizing ideology, and only turned to the Muslim Brotherhood or Salafism after the nationalist leaders failed.
If Kook could head Zionsim first, he'd be speaking to a population that thinks like him. Herzl was the oddball in his time, not the other way around, which is part of the reason his theory didn't catch with the populace
No, he'd be speaking to a population that would reject him, because the shtetl Jews saw no reason to emigrate. You're under the impression that because under contemporary Israeli-Jewish definitions of religiosity the shtetl Jews were Orthodox, they'd be a good fit for religious Zionism. This is not the case. Religious Jews in turn-of-the-century Europe spoke Yiddish, and reserved Hebrew for liturgy; Zionists, including religious Zionists, revived Hebrew in secular usage. They based their life on small-town existence, and if they wanted more, they aspired to become like the urban middle class; Zionists came up with the idea of muscular Judaism, in which Jews would shed their middle-class intellectualism and become people of the land. Nationalism is all about urban middle-class romanticism for the peasantry; the actual peasantry's opinions are never relevant to the urban romantic. The easiest way to see the difference between the shtetl mindset and the religious Zionist mindset is that in Eastern Europe there was an entire tradition of draft dodging among Jews, whereas religious Zionists today fetishize the military and the men make a point of serving in combat units.
Ultra-Orthodoxy bears more similarity to how the Jews lived in the shtetls, and remains non-Zionist... but even it has evolved a lot in the last hundred or so years. In the shtetls, the men worked, and only the best student in each generation would get to stay in the yeshiva and become a rabbi. Nor was there much spatial segregation between men and women. Nor is there much of an agrarian tradition anymore, what with Israel having a) close to 100% urbanization, and b) a farm sector that's still dominated by the kibbutz and moshav movements, which are almost exclusively secular and (pretend-)socialist.
Of note, there was such a thing as religious Zionism. It wasn't just Kook; he didn't invent this movement, but was speaking to a current of middle-class urban Jews who remained religious, and disliked the secular direction that mainline Zionism was taking.