But isn’t that just another way of saying that they haven’t thought it through? Again, my point is that the emerging church is extolled as wonderfully innovative and radical, and it puzzles me that that doesn’t show up in the way they use the Bible.

NO, that is NOT another way of saying they haven't thought it through. It is another way of saying that they and hundreds of others HAVE thought this through. Just because they don't fill in the details in this book doesn't mean they haven't through it through.  When you read those essays you may hear something that you feel is radical and want detailed exegesis. For most of us, the concepts are already part of our theological DNA so we are not apt to unpack those concepts everytime we speak or write.  Just because they didn't upack all those ideas and fill in the blanks with detailed references doesn't mean they treat the bible lightly.  Numerous quotes and references does not make an book biblical. They could make it dry, packed with references and footnotes, but void of inspiration like many other books I've read. Do you give refunds for "the coming of the son of man"? (I'm just kidding!!! wink wink)

The problem we still face (it’s not going to go away that easily - and we shouldn’t let it) is put very sharply by your statement ‘the gospel is about social justice’. That simply does not serve as an adequate account of the New Testament

Yes it does serve an adequate account of the New Testament. Actually it serves as an adequate account for the whole Bible. The entire point of the entire narrative of Israel is social justice. The story starts with the words "no more bricks". It continues to the idea of the first document of workers rights ("Remember the Sabbath and keep it holy") and it finishes with the hope for  the end of Roman Imperialism. The whole point of the bible is to craft a just society.  Every story is there to paint a vivid picture about the need and hope for social justice.  Everything else is commentary.  What story from the bible is NOT about social justice?  Some books are written at the macro level and others are very detailed.  This book was obviously the former.