Отличная статья для любителей (и не) XML

http://c2.com/cgi/wiki?XmlSucks

Раскрыты темы:
# It's too complex for what it does.
# It's too hard for programs to parse and too verbose and unreadable for humans to write.
# The benefits of "everyone is using XML, so we should too" are usually outweighed by the costs of time, training and mistakes involved in understanding it.
# Because it's increasingly used for data interchange, it is promoted as a data storage model. XML is only a data encoding format.
# or just comments wrapped around data. Too much comments and symbols.
# <Are the comments part of the markup/>, when they could just be comments instead.
# Encourages non-relational data structures
# * ie. Data is not even in 1st normal form let alone 5th.
# Poor OnceAndOnlyOnce syntax factoring
# It's a poor copy of EssExpressions
# It is ExtremelyInterstrangled.
# Perhaps worst of all too many programmers don't understand the need for data description languages with broad support.
# Transformations, even identity transforms, result in changes to format (whitespace, attribute ordering, attribute quoting, whitespace around attibutes, newlines). These problems can make "diff"ing the XML source very difficult.