James is undoubtedly right that the Gospel of Thomas, to cite an obvious example, stands no chance to replace the four gospels found in the New Testament in contemporary religious culture or culture tout court. Not even a writer as delightful as Elaine Pagels could pull that off.
Still, I believe very strongly in the value of reading ancient literature outside of that understood as biblical, for its own sake, and with a view to exploring commonalities and differences with biblical literature. To use examples familiar to me, there is a sense in which I came to understand biblical prophecy only after coming to grips with prophecy as attested in Mari, Assyria, and the Iliad for that matter. The same applies, mutatis mutandis, in the case of a gospel like that of Thomas. The specific characteristics of the four canonical gospels are much clearer against the background the gospel of Thomas provides.