That's not really at all comparable. With writing, unless you get an advance on an unwritten book, you first work for months or years unpaid, and then (if you're lucky) you get an up-front sale payment and then royalties for a while. What would you think if you started a new programming job, kicked the bucket after 29 days, and your employer tried to claim that they didn't have to give your last paycheck to your family because you didn't finish the month?

Death or 15 years seems fair to me.