One of the things that people tout as a strength of XML is its “human-readability”. But we pay a big price, in terms of CPU, bandwidth, and storage, for the terabytes of XML that are parsed, shuffled, and stored without a human eye ever reading them.
By the way, you ever tried to read some of the stuff that comes out of, say, OpenOffice? To call it human-readable is a bit overstated. And don’t get me started on XML-based scripting languages! I mean it, don’t!