"Why are so many of today's novelists driven to fictionalise the lives of their illustrious predecessors?
One reason, I suspect, is that novelists enjoy inhabiting their heroes' worlds and projecting their imaginations into the gaps which are off-limits to biographers. But do such books amount to more than a literary branch of the heritage industry?"
Most of the points in this piece on the UK's Independent are well taken.
The majority of fiction writers (with a few exceptions like Hemingway) are introverts. What is interesting about them is their work. Their lives? Well, not so much.
And anyway, the biographies of writers are better served by the genre that already exists for that purpose: nonfiction biography.