[derefr]

That presumes you want to send a lot of binary data. Sometimes you just have five bytes or so. (E.g., as in the article, an un-decoded string.)

(Still, you're right, I admit to having been able to avoid any work painful enough to teach me XML arcana. I was actually thinking of one of the many variants of "Binary XML" I had read about recently, and assumed the typing was bijective to XML's own types. In other news, BSON of all things has a raw-binary type.)