If it's acceptable to write a story set during, say, the Battle of Dunkirk, or the Great Depression, or in the aftermath of the San Francisco earthquake, I think it's acceptable to write a story set in modern Kosovo or Chechnya, or occupied Baghdad, or post-earthquake Haiti. But just as, say, The Grapes of Wrath would have suffered without Steinbeck's craft for making characters human in their place and time, for representing them as they are, a story set in post-earthquake Haiti is going to suffer if the author relies on stereotype and poorly-thought-through speculations to generalize about an entire country full of people.