Why don't we write configuration files in D instead of JSON?

[Guido via Digitalmars-d-learn]

> have a look at  `dub convert` - in your case e.g. `dub convert 
> -f sdl`

This dub convert command is weird. It works as `cat dub.json | 
dub convert -sdl' and makes a nice SDL file called dub.sdl, but 
it blows away the source file, which I've never seen before with 
piped output from cat. I don't like deleting the source file 
being the default behavior.

Also, commands like `dub convert -f sdl dub.json' and variations 
of that sort don't seem to work as a command. They have errors.

What's the weirdness here?