I keep trying to explain the difference between a configuration format and a data format. A configuration format is for humans. A data format is for computers. Try to make one format good for both, you end up with one format that sucks at both.

Another fun thing about configuration: it's a great indicator of poor software design. If the configuration can be very complicated, in one single format, in one big file, look at the source code and you'll find a big ball of mud. Or even worse, it's lots of very different software that all shares one big config file. Both are bad for humans and bad for computers.