Americans want cheap Nikes for the masses and as long as the demand is increasing you might as well lower the tariffs.
Until the attritude of the American consumer changes (buy cheap and lots of it), you might as well go with the flow.
Ethics seems to have little priority between the pocket book and merchandise.
In at least one class action pending in the U.S. Ninth Circuit Court region there has been developed extensive evidence of American companies exploiting child and indentured labor in their manufacturing and assembling plants in the far Pacific islands that are either U.S. territories or in a protectorate status. The companies to which I refer are those we see everyday in mass merchandising stores all around the country and who boast about low retail prices. They use labor contractors to import "guest" workers, pay them less than slave wages and house them in abject squalor.
The point being, if we are to be critical of internal Chinese labor practices---and it is certainly appropriate to do so, we should similarly do the same with respect to those American companies who, in taking advanatage of being able to sew a "Made in the U.S.A." label into a pair of jeans, also engage in the same wrongful practices. Perhaps the difference is that the American companies have been successful at keeping their practices quiet and the American public elects to look the other way because of the misleading label we see in the stores.