It is not about a right or a wrong. English is very flexible, and you can communicate the idea in multiple ways. To say; "My grandfather died 30 years ago. I never met him."; is a very clear communication. Your alternative reads awkwardly. You would not write; "I have" if he has been dead for 30 years, because "I have" basically suggests that the Grandfather is presently living, even though you have not met him. When you write that he died 30 years before, and afterward indicated that you never met him. all the information that is relevant is presented in a simple, straightforward manner, which avoids any ambiguity or contradiction. In trying to write an alternative, you run the risk of creating confusion as to time and action.