Sometimes it is and sometimes it isn't important to research an author. If you are reading an author from the past, it's usually important. Writers do not write in a vacuum. Knowing about the culture and historical elements will help. Some writers also have interesting agendas or personal problems, and it helps to know those. Generally, you don't need to research current authors.
No matter what the conventional wisdom is, there is always something of the artist in his/her (hello, kplhardison) art. How can there not be? Is not perception a physical and psychological phenomenon? And, not only is the perception of the artist physically and psychologically produced, but it is also affected by the historical context of the artist. For instance, would Ernest Hemingway still write as he did had he not experienced the horrors of the Spanish Civil War and of World War I? Probably not. Would Nathaniel Hawthorne have written with such introspection of character had his relatives not been tarnished Puritans themselves? Indeed, not.
Now, the work of art can be judged solely on its own merits isolated from historical context and authorial voice, it is true. Nevertheless, as Emily Dickinson wrote, "There is a certain slant...." that is generated from the pen of the artist that gives a work its full intensity and meaning. Why else would different people be moved and interested in certain authors' works?
However, there are schools of critical theory that say reading about an author's life is irrelevant to understanding the text and therefore actually detracts from the meaning of the text. Part of the argument goes that if you are preoccupied with thoughts of the author's life and the influence of that life on the text, you are not actually reading the text, you are, in fact, reading your own intertextual interpretation of the text. This is thought to be a disservice to the text. Having said this, one reason to read about the author first may be to inspire curiosity about what such a person might have to say.
As I agree with the other posters, I find that the research of an author is important because it offers a background in the period from which the author wrote.
Knowing the characteristics of the Romantic period help when reading Shelley or Dickinson. A reader will come to understand more deeply why an author fits into a specific genre and how the characteristics of their writing is evident of the period from which they came from.
Another reason that research is important is that it gives the reader a more global understanding of the author and the world at the time. Terms used in the text have often changed in meaning or usage (think Huck Finn or To Kill and Mockingbird). Readers need to understand the usage of the terminology and its appropriateness to the era.
Another reason to research the author is to understand important references and allusions within the work. In To Kill a Mockingbird for instance, the reader needs to be aware of certain influences of the time such as Jim Crow laws. The reader wouldn't understand all the references to innocence and injustice without knowing a little bit about the author and her time period. This can be especially true for non-fiction authors. Take the book Night by Elie Wiesel. If you didn't know that the author had survived a concentration camp during the holocaust or a least have an understanding of what happened during the holocaust, the book wouldn't make as much sense. Books like the Iliad and the Odyssey require research before reading. It would be impossible to understand the story without a good deal of background information.
I love this question, because it is one I get often from my students when I make them research an author before we start a new novel or play. Some of the reasons I give them why this is an important step are:
1. An author often writes from he or she knows. To understand fully why an author takes the position he or she does, or sets a play where he or she does, it is helpful to know what influences shaped his or her beliefs and experiences.
2.Knowing when an author wrote and published his work will help you figure out the style of his writing. For example, Hawthorne writes lengthy, compound sentences because it was the prevailing style of the day, whereas Hemmingway writes in a journalistic style, as he lived in a more modern era where that was the style of choice.
3. Tone can be more fully understood by understanding the personality of the author.
4. In researching the people that were important in the author's life, the reader can often find the basis for the major characters in the book, which allows the reader insight into why the characters behave as they do.
Now a days many new literary theories have come up which state that read the text. Yet it seems to be important to research an author before reading because literature is called the mirror of the age in which the author lived. Certainly there will be some features in his writtings of his age and therefore literature of various ages have been ctegorised as Anglo-saxon period, middle english period, restoration, romantic, modern, post modern and so on. Secondly every writer has his own style of writing and he is influenced by his age. Tennyson and Browning tried to come out of the Romanticism and do something new. Thirdly, Social, economic, religious factors also cast an impression on the author. Lastly, an author's fmily background, racism, marginalisation, physical deformation, love,betrayal etc also effect his writing.