Re: Magic Sales Bot
On a more serious note, machine prose generation is already widely used commercially, for example in sports and financial reporting, and in the niche non-fiction market. Philip Parker's system is the best-known example of the last; his Icon Group International claims to have published over a million titles, either in electronic form or print-on-demand.
The first documented commercially-published machine-generated novel seems to have been True Love from SPb, in 2008. It wasn't very novel, actually, being a style-transformed pastiche of Anna Karenina,1 but it was produced by software. There appear to be a number of commercial projects in this area so it's likely there are quite a few more commercially-published machine-generated novels by now.
And of course there is extensive academic and commercial research in the field of machine-generated prose, and related fields such as machine-assisted prose generation.2 Doyle's efforts are not representative of the state of the art. A few years back CACM had a cover story on computational journalism, for example.
(Note, too, that in some other fields computer-generated "creative" work has been around longer and had greater success. Computer-generated classical music was winning praise from critics in the 1990s.)
1If you're going to steal, steal from the best.
2I've done some work in computational rhetoric, for example. Computational narratology, computational adaptations of formalist and structuralist literary analysis, computational folklore, computational psychology ... there are many cognate fields of research.