It doesn't matter whether the characters are important enough, this article is about 'List of Dragon Ball characters', not 'List of important Dragon Ball characters'. Regardless of how important they are, they should be listed in the article. Also, Dr. Briefs and King Vegeta are the fathers of protagonists and did contribute to story-lines. If only important characters should have sections then why are there separate sections for Oolong and Pu'ar? They're not important enough.