Trader is indeed an unattractive subclass, as it is only beneficial in the unlikely circumstance in which a region finds that it has no prospective trade offers open to it. As food-consuming regions and food-producing regions are spread out fairly evenly in most cases, and because global food production is always at a surplus, it is seldom the case that a merchant, who's abilities are only modestly superior to a Lord's, is able to make use of his or her trade in a productive manner.