would you say that bacon was right in thinking that the popularity of essays were to their practical value alone

The answer to this question, regardless of which of Bacon's essays it applies to, is based on whether or not the reader of the essay pays attention to the advice and philosophy shown in the essay. Essays are somewhat like advice given by someone whose wisdom should have taught them one or more lessons about life. If one reads an essay - a straightforward piece of writing which is nonfiction - and finds that it is applicable to oneself, then the philosophy related to "truth," "marriage," "studies," or "life" will be implemented into one's life.