Grandpa's death isn't tragic because it is not unexpected. Grandpa didn't want to leave his house. He says that it is his home and he won't leave it. The family has to drug him to get him on the truck so they can leave on their journey. He is like the tree that has been in the ground for a very long time and has extremely deep roots. It cannot be uprooted and transplanted like a young tree with shallow roots can. Grandpa has been on the land in Oklahoma longer than anyone else in the family, so his roots run deepest. For this reason, it is inevitable that once he is removed from his land, uprooted, he cannot survive. He would have been miserable, had he lived, outside of Oklahoma. This is also the reason that Granma dies almost as soon as the family enters California. She also cannot survive in a new world because her world is gone and like an old tree, she cannot be transplanted any more than Grandpa could.