Couple this with the fact that quite a few missionaries are not spiritually qualified to be out on the field in the first place, and you have a clear and obvious need to diversify the risk. I am not trying to be particularly inflammatory or cynical here, but one of the ways you can tell that a young college student is starting to struggle in his Christian walk is that he is starting to think about missions. What better way to quiet the spiritual churn within than by becoming a missionary? Missionaries are spiritual people, right?
Douglas Wilson