Now in 2015 we have XML prejudice and aversion where people trash XML as the worse possible format. As with many things it has its strength and weaknesses a couple of them being that a parser exists for almost all programming languages and the syntax of XML is probably the most widely understood (given so many people know HTML). And while XML is complicated there are far more complicated formats (YAML).
What we have today is format creation fever. Particularly in configuration languages. Hucon, TOML, YAML, JSON, sort of JSON formats (HJSON or whatever it is).
...when all we really needed all along was S-expressions.
Wish I could upvote this more than just once.
OTOH you kind of need hashes/maps in the real world (sexprs can provide this by syntax, but not necessarily by agreed-upon function). And Unicode. And standard representations for the base datatypes. But aside from that there's no reason to enter the Sea of Arbitrary Anglebrackets.
I believe Clojure's EDN format offers all of the above https://github.com/edn-format/edn