Just to throw some balance to the discussion, let me be the lonely voice of dissent.

What the author says about XML could be said about almost any other technology available to store/share data. There is no universal solution that can be adapted to every case. For simple cases, an old fashioned text file is more than enough, but as the complexity increases so does the solution. Files used by a single application can be whatever a programmer wants and they usually work fine, but as applications begin to interact with one another the simple solutions show their limitations. Interaction implies well defined interfaces, and XML provides an great way to describe and publish an interface. Not the only way, for sure, but it has distinctive advantages over other ways like COM, IDL, header files or EDI. If you program in an isolated environment this is a non issue, but if you need to write programs that consume data from vastly different sources, you need some standard. Enter XML. The wide adoption of this format has made it the de-facto standard, and that's something GOOD if you are in the business of data publishing/consumption.

By claiming that XML is overly complex, the author is ignoring one of its key features, which is the fact that there is a standard, and this fact has made possible the development of many tools and language constructs (most of them freely available) designed specifically to deal with all the complexities of XML. This is what makes XML a good choice for many projects (notice I don't say "for every project"). As an example, compare with the still popular comma delimited file: If you are processing information sent in that format, you either trust each line has the same number of fields or write code to deal with exceptions. Same for the actual data: if the third field has to be a date, you have to write your own code to check for it. In general, you end up writing code that is custom made for a particular file, and if the the file format changes, you usually need to change your code. Compare that with the XML solution: once you agree on a particular schema (including a DTD), all the grunt work is already coded in most XML frameworks, you only worry about processing the data.

Maybe in the old days XML had to be manually processed and validated, but we've come a long way, and nowadays most XML traveling the net is never seen directly by any user, it's just processed by highly optimized code that works precisely because for once we have a format with almost universal acceptance. I don't see anything wrong with that.

If you don't like XML, you are free to use whatever format you like, but if you need to interchange information with the rest of the world, don't expect everyone to adapt to your own format. In fact, just about everybody already adapted to XML, so why not use that to your advantage?.