...feel free to comment with additions...
"Life isn't divided into genres. It's a horrifying, romantic, tragic, comical, scifi, cowboy, detective novel."
...and I don't feel like sifting through thousands of pages to find the exact quote, but in Stephen King's "The Dark Tower" series, Roland (the main character) says to another: "Does everyone in your world want only one flavor in their stories?"
...sensing a theme? ;) I love cross-genre stuff... There's no reason writers or readers should limit themselves. Also... never underestimate your audience.