Free trade makes countries richer. This is true for both rich and poor countries, but it is especially true for poor countries. And when I say "free trade" I mean just that, not "fair trade" which is correctly seen by third world governments as being a hidden form of rich-world protectionism. The WTO should not consider environmental or humanitarian concerns when ruling on trade disputes. Those wars are better waged in supermarkets, where consumers can choose between dolphin friendly tuna or the cheaper stuff.
Again, i encourage folks to read Krugman, he puts it better than I. In future I will assume that folks have read that article.