Why was Grandpa Gohan never revived with the Dragon Balls?
He expressed that he does not want to return to the world of the living ones. Goku fought against his grandfather (masked fighter) at a tournament hosted  by Fortuneteller Baba. After revealing his identity to Goku, Upa (the boy whose father was killed by mercenary Tao and Goku went on a quest to gather the Dragon Balls and revive his father) asked him if he want to be revived instead of his father, but Gohan replied that there are a lot of "babes" in the after world and that he would like to stay there.



The chapter in question is 108 from the original Dragon Ball.