Title should read:
Why crime novelists should stick to writing crime novels and not redundant essays.
Genre writing
is cliché. By its very definition it promises a similar and repeatable experience to the reader, so it should be no surprise that characters lack complexity and depth; whether they be female, male or the four hundredth copy of Philip Marlowe. There are good reasons Italo Calvino never wrote a mystery and John Steinbeck never wrote a paranormal romance.