The mouth of the Earth

Why was the mouth of the Earth used to punish Korach and his followers, couldn't a bolt of lightening or death by plague sufficed as a punishment?
Read more: http://www.shortvort.com/korah-parasha/12276-korach

Korach had many outstanding qualities. He hailed from a distinguished family, was a talmid chacham, possessed extraordinary wealth, and was a very wise man. How then could he have fallen so low to accuse Moshe of selfishly taking power and prestige for himself, especially after the Torah testifies about Moshe, “Now the man Moshe was exceedingly humble, more than any person on the face of the earth.”? How could he possibly accuse him of possessing the contemptible trait of arrogance?!
Read more: http://www.shortvort.com/korah-parasha/12134-blinded