The Protestant Reformation was, among other things, a reaction to the late Medieval church and a return to the Church Fathers.  The sixteenth-century Reformers were highly critical of the doctrine of faith espoused by their Catholic contemporaries, the Schoolmen (the Catholic theologians at the various universities). By and large, later generations of Protestants seem simply to have taken the criticisms of the Reformers as the final word and assumed that they would not be likely to find anything of permanent worth in the Schoolmen’s teaching on faith – including the teaching of Aquinas.  And so today Aquinas’s views on faith are practically unknown among Protestants. (Arvin Vos, Aquinas, Calvin, & Contemporary Protestant Thought, pp. 1, 2)

I would add to this that many Protestants assume that the arguments of the Reformers, John Calvin specifically, against the Schoolmen were arguments against the entire Medieval scholastic tradition. McGrath in his monograph on Calvin points out that these Schoolmen were teachers in the French Sorbonne who were not espousing a pure scholasticism.