If You Can Spell "Verisimilitude" Without Peeking, I'll Give You a Cookie.
"One of the major purposes of literary setting is to establish realism, or verisimilitude." (111)
I completely agree with Roberts on this one. There isn't too much to say on this subject except that realism and setting should go hand in hand. If a setting is too off-the-wall, the whole narrative will fall apart. A reader won't so much be spending time trying to relate to your characters as wondering why a Kansas farmer is at a McDonald's on Mars. There is some merit to fiction because it adds an element of fantasy that some people find to be very interesting. However, there's a big difference between fantasy and ridiculousness.