How does being subjective contribute to creating an informal tone of an essay?
Gosh, in my opinion, I’m not sure that it does. I would think being OBJECTIVE would contribute more to the development of an informal tone. Being SUBJECTIVE implies that you have an attitude or a bias about what you are writing about, so I would expect your tone to be more passionate. Being OBJECTIVE, on the other hand, suggests that you still have an open mind about the subject, and would therefore be able to develop a more informal, professorial-type tone. Others may disagree with me, and that’s fine. It’s just my SUBJECTIVE opinion.