Edd Dumbill reports on unmet expectations that Binary XML would cause more of a raucous response.
My off the cuff theory is that by now every developer on the planet has implemented at least one kind of kludge for sending their own encoding of XML over the wire more efficiently the default bulky representation format that is XML. Because the problem has been solved just good enough by their own quick hack, developers might easily assume a standard binary format for XML would be trivial.
My favorite approach was, is, and probably ever shall be Lisp. Convert from XML to Lisp format. Convert to binary if necessary. And use an efficient, incrementatal protocol if needed beyond that. (One reasonable example is found in that wonderful journal, Software Practice and Experience, in a paper called "Efficient Binary Transfer of Pointer Structures". (PDF)
In any case, my response is to just kind of chuckle. There are a number of variables in choosing a binary representation of semi-structured data intended for various uses. This is not a one-size fits all problem, XML is a simple idea complicated by a wide range of intentions.