A theological problem with "postmodern" exegesis

I place the word "postmodern" in scare quotes, as I don't think that much of what passes for "postmodern exegesis" is really (necessarily) postmodern. As far as I can see, what Brevard Childs says here could fit very nicely with the theological hermeneutic of the postmodern philosopher/theologian Jean-Luc Marion (see his article "Of the Eucharistic Site of Theology"):

I remain critical of those interpreters who attempt to force exegesis into narrowly defined structuralist categories, or who restrict its only legitimate role to synchronic analysis. The relation of the synchronic and diachronic dimensions is an extremely subtle one in the Bible and both aspects must be retained (cf. Childs, Biblical Theology, 98ff.; 211ff.). Basically, my resistance to much of postmodern literary analysis derives from theological reasons. Although I have learned much from modern literary techniques, I differ in my theological understanding of the nature and function of scripture. I regard the biblical text as a literary vehicle, but its meaning is not self-contained. Its function as scripture is to point to the substance (res) of its witness, to the content of its message, namely, to the ways of God in the world. For this reason I remain highly critical of many modern literary proposals, which are theologically inert at best, and avowedly agnostic at worst.

Childs, Isaiah, 4.