I guess this makes sense since the book wasn't suppose to be officially released until March 2012. The resignation of Mr. Jobs in August moved the date to November and finally late October with the news of his death. Because of this, perhaps the publishers rushed Isaacson to finish the book before he 'felt' he was finished with the story.
The author discussed potential plans for expanding the already 630-page book in the future. One possibility is doing an extensively annotated version. Another is writing an addendum that addresses the period surrounding Jobs' death. Fleshing out the details seems like a logical next step, since Isaacson believes the Apple (AAPL) CEO's story will be told for decades or a century to come. "This is the first or second draft," he said, referring to his book's role in documenting Jobs' life. "It's not the final draft."via cnn