For pure serialization, XML starts looking like a bad choice compared to YAML and JSON, but if you want to do anything more then serialization then XML starts winning ... the closer the data you are encoding starts looking like a document then YAML and JSON lose.

XML is better as a general purpose format and I tend to choose general solutions if what I am building has a lot of volatility in its requirements. I see JSON and YAML as a natural optimisation to be considered nearer the end of development versus considering them as architectural 'pillars' of a solution ... and yes I would rather lose in terms of speed of development upfront and manage 'near future' requirements then use YAML/JSON because its fractionally quicker then XML to work with.

I think the main problem is using XML everywhere when its power will never be needed ... basic config files are the main culprit here.