XML does have a number of technological problems, but ... the technological problems can be managed [and] the political and commercial advantages of working with the same open standard as everyone else are enormous.
One bogus criticism: Crane's complaint about the verbosity of element names. With today's disk space, processor speed, memory, and compression, it's farcical to think that we need to sacrifice human readability by taking advice like this: "Avoid repeating the element name in the closing bracket."
Somewhere, a coder who had to implement a spreadsheet on a circa-1981 IBM PC in 16K of memory (expandable to 64K!) is reading this and mocking us. And he's saving his work on floppy disks bigger than his head.
As he notes on his site, Crane originally produced the slides as XML.
It's not about disk space. It's about clarity. When you're trying to reason about a sophisticated algorithm, the elegance of the written expression is paramount.