I just mean that there's nothing inherently sincere about plainness and simplicity. Some people adopt a plain and simple style disingenuously, and others write in a more flowery style out of a genuine aesthetic motive. In French, 100 years ago, the kind of style you're advocating would have been the "marked" case. That is, readers would probably have attributed disingenuous motives to someone who chose to write a history book in the style of spoken conversation.