I think authors are just realizing there's no real reason to feel limited to a narrow set of genre rules in their writing. There's no reason a mystery novel can't have fantastic elements in it. Similarly, there's no reason why your epic fantasy series can't have elements of a mystery.
Patrick RothfussI have, of course, been called many other things. Most of them uncouth, although very few were unearned
Patrick RothfussI've got a solid grounding in history, sociology, anthropology, philosophy, etc etc. That means I actually have a good idea about how societies change and evolve. I know how a lot of them have actually functioned through the years. I can put together a culture that's cool and different, while still being logically consistent, so that it feels real. So many fantasy worlds are either implausible, cookie-cutter, or both. Mine aren't.
Patrick Rothfuss