My grandparents were grandma & poppy, and grammy and pappy. My parents were/are mammaw and pappy, and my husband's parents are "who are those people?" (sorry, no bitterness there)
Might sound silly, but I want my grandkids to call me something different or off, like Lovey or something like that. A friend of mine's grandkids call her Peachy. When my son was little, he insisted on calling me Dee or Deeya. We have no idea why he started saying that, but it stuck for quite a while. It was so sweet and charming that he had his own special name for me.
I agree. I don't think there should be any power struggles over what a person prefers to be called. We might not agree with it or feel like their reasons are silly, but we should respect it.