What is an Author, Anyway?

Since I seriously doubt that anyone has yet had a chance to read the Foucault essay (after all, we're still on day-one of the course), I thought I'd write a few words about the essay and pose a question or two for discussion (please, engage with one another in the comments; discussion here counts for participation credit).

As for background information, Michel Foucault was born in 1926 and died in 1984, and was a prominent public intellectual and political activist. In his political engagements, he was particularly involved in gay rights and prison reform movements. Hence his rather famous books were entitled "Discipline and Punish" and "The History of Sexuality." He had doctoral degrees in both philosophy and psychology, the latter of which he earned first, publishing his first essay as an introduction to a book by the existential psychologist Ludwig Binswanger in 1954. His first major work was "Madness and Civilization," which called into question all conventional understandings of mental illness.

Foucault's methodology is typically classified (by his own terms) as Archeology and Genealogy, which is to say, he seeks out the most fundamental levels of a phenomenon in question and traces its development, rather than seeing it as timeless or pre-given.

Hence, the "author" cannot be taken as a given. It is true that there is in fact someone who writes a given text, but there is a difference between the writer and the author when the reader comes into play. The word "author" implies "authority" and is thus taken as having an authoritative and true interpretation of the text he has written. However, even psychoanalysis shows us that we are not always fully conscious of what we right, so we already find the concept of the author to be in question.

Foucault considers the "author" not as an individual, or as a structure, but rather as a function: that is to say, "I, the author, mean such and such." And examines how the author is constituted.

My question to you, from which you may stray as far as you like in discussing interesting points in the essay, is the following: why is the concept of the "author" so important and embedded in our culture?