Wickedness is easier to display in literature than goodness. Evil characters are easier to develop than good characters. So says crime novelist Phyllis Dorothy James, or P. D. James. In an interview with Ken Myers from the 1980s, James said this:
I suppose that wickedness reveals itself often in action. Goodness also does, but is on a quieter plane. Good people often reveal their goodness through the whole of the quiet revelation of their character in the ordinary events of life. And if a good person is being courageous he’s probably being courageous in facing rather ordinary troubles—sick children, a sick wife, an uncongenial job. Wicked people are murdering. It’s more dramatic. Goodness is very seldom dramatic, I think. And it’s much more easy to write about drama.
If evil is more dramatic and more easily communicated in literature it is also more easily read. On the other hand, goodness in literature is difficult to write and is–I think–more difficult to read.
The bold drama in crime fiction is less demanding of the reader. The subtle drama of goodness we read in novels like those by Marilynne Robinson is more demanding. And this is because reading literature for its goodness requires the reader to pick up on the subtle drama.