I like XML but...

... I don't want to use XML to configure my *NIX system, Period.
The beauty and simplicity of a *NIX config-file is based on the fact that it is stored as plain-text — to be edited via a text-editor, via a command-line editor, or even via a sufficiently equipped cell-phone. Every person who knows what he/she is doing is able to create scripts to maintain and monitor the files used for configuration; changing the format to XML adds just another layer of complexity to the daily workload.
Don't get me wrong here, I use XML every day; be it to write books or articles or to manage the transition of data to, from, and between databases. It is a lingua franca that enables us to migrate our data or intellectual property from one format to another or — in a perfect world — to store said data in a format that allows us to validate the structure it is stored in.
But (this is a BIG but) I want to be able to make sense of a configuration file _without_ resorting to some kind of specialized editor, because this special editor might not be available on every platform in use to do daily maintenance, it's that simple.