Aside from taking creative writing courses to hone your craft and get critical first-reader feedback on your work, any writer who was not an English major should give considerable thought to taking literature courses. It is a commonplace that the better you are at critically reading a text the stronger a writer you will be. Reading the classics is also important, especially if you want to consider yourself a well-read individual. If you’ve picked up a few classics as an adult and enjoyed them, you should think about taking a course in which works from that literary period are read and discussed. I think it’s safe to say that it will expand your mind as a reader and a writer, and truly give you a new vision as to what you hope to accomplish as a writer.
But the most obvious and pressing reason why any writer who wasn’t an English major or an MFA student should take a literature course is to see how the masters did it. I think the most valuable thing a writer can do to show respect for their vocation is to honor some of the old masters by reading them in a classroom setting, with readers (and probably dreamy-headed writers like themselves) interested in understanding the texts and authors from a critical and historical perspective that reading on one’s own cannot entirely yield. Having a brilliant professor in the field who lives for the literary word and the period in which the book was written (or set) is absolutely essential as well. If the most intelligent professor I ever had didn’t teach me all about Milton and Paradise Lost in my first semester as an undergrad I would not have been an avowed Miltonist until three years later when, thanks to another well-educated professor, I read William Blake and became a Romantic and a Blakean to this day.
Taking a literature course from a writer’s perspective will enhance how you write and what (or who) you write about. Taking a course focused on a single literary figure (like Hawthorne or O’Connor) would be a great asset to a biographer who wishes to write about that particular author, giving the biographer a greater understanding of the author’s experience and vision of his or her time and place (through an examination of their texts) and why their work is so important to the literary establishment.
Writers of historical fiction would also do well in taking a couple of courses in their time period, not just literature courses but history courses as well. The wonderful thing about literature is that it is not written in a vacuum; history and culture shape the writer even before he or she sets pen to page. The author’s perception of their time and place or the historical period about which they are writing permeates their fiction, no matter how you may look at. We are all products of our time, or of how we see (or are taught to see) other historical moments and periods. Historical fiction is difficult to write because you have to be accurate in your descriptions, even in how you delineate the social customs of the time and your characters’ language. Studying the major fiction and poetry of that period in a classroom will give you not only a creative but also a critical lens with which to read the literature of that age and write fiction that takes place within it.
Speaking from personal experience, my writing would not be what it is and I would not have written so much poetry if I weren’t an English major. A number of my poems are literary in subject and even more of them have a wide variety of literary allusions. In short, my writing has only become stronger thanks to the reading I have done for the last twenty years, and because I took courses in literature as well as creative writing, not to mention art history and philosophy. So if you wish to truly develop your skills as a writer, explore genres other than your own, and gain knowledge of a literary movement or historical period that will make your work all the more accurate and beautiful in its narrative, then it would benefit you to take a few literature courses.