I have often been asked: Why write?
I don't think there's a definitive answer to this. Ultimately, each writer is free to offer their own reasons for picking up a pen. But it seems to me that Roland Barthes is right to emphasise the need for pleasure. Writing isn't always easy or a great deal of fun, but it does strangely gratify (which is why it's essentially an erotic activity and not a moral or scientific one).
And it does this both in a negative fashion - by warding off boredom, for example, or provoking enemies - and in a more positive manner; writing pleases because it enables one to become-other. By decentring language and deterritorializing the individual, writing produces not only new meanings, but new selves.
Writing, therefore, has a crucial task to perform; it generates difference and contributes to smashing the Stereotype and the hell of the Same (i.e. society's fixed symbolic order). Writing lets us lose face, waste time, and think dangerous new thoughts.
This is why writing is also a distinctive politico-philosophical activity; it lends substance to the idea that there is greater value in playful poetic musing or posting bits of theory-fiction on a blog, than there is in an honest day's work.