Shavua Tov. Rabbeinu Bechaye explains why Moshe Rabbeinu asked Hashem to see to it that Korach and his group, die in a way that was never witnessed before.
Aside from Korach challenging the authority of Moshe and Aharon, he was undermining the authenticity of the Torah. He asked numerous questions that were mocking various Mitzvot. He made fun of such basic Mitzvot as Mezuza and Tzitzit.
Rabbeinu Bechaye felt that such challenges of the truth and beauty of Hashem’s Torah, needed a very strong response. It was for this reason that Hashem opened the ground to swallow up Korach and all that belonged to him. Belittling Hashem’s Torah was something that could not be tolerated.