However ultimately we made the decision that the non-XML syntax (or you could say more SQL like syntax) of XQuery was going to attract more developers in the long run, in the same way the developers on the whole find XPath an easier file-path like syntax to write.
The next time you are tempted to write a programming language in XML (or add conditionals, loops, etc. to an XML specification), give in to the dark side and pick a decent programming language instead. Possible exceptions to this rule are if you’ve implemented n+1 programming languages already, at least one of which must be in use by one million or more people. Because then maybe you’ll know what you’re doing. Otherwise, just give up.
Remember, XML is just fancy syntax over plain-text (most everything is anyway), and unless you’re qualified to write a programming language anyway it’ll just turn out mediocre.