It seems, then, that the use of a rhetorical question mostly depends on your tone and your audience. Stephanie Nolan, an editor for Online Writing Jobs, is a graduate of the S. Newhouse School of Public Communications at Syracuse University.
But it also depends on the writer and their comfort level with using them. Since college, she's both edited and written film scripts, press releases, fictional stories, and articles.
It can even be a necessity in some situations where any other type of sentence just wouldn’t do what you want.
It’s hard to hammer a nail when you’re unnecessarily limiting yourself to screwdrivers and large rocks.
Here is an example: "Skepticism is when you don’t really know anything." This is a bad definition of skepticism. They should not be reported as questions (see Danger Sign 1) or events (like "is when.") There’s nothing grammatically wrong with "also said …" (like there is for a theory described as "is when …" or as a question).
However, when I see the above phrase in an exam or paper, I am warned that the student is not really following Hint #1) above.
In an academic setting, they’re especially frowned upon.
But in a public speech or a TED talk, for instance, they’re very often used to call attention and point out main discussion points.
Think of it this way: They’re not real questions but rather statements given in a question form. Some writers can and have used this technique to great effect.
And their use has become clichéd due to overuse and ineffective use. To say that rhetorical questions are all bad is like saying hammers are all bad.