cut/sed are usually used for the program's output, not their configuration files.
And if there was that common configuration format, you wouldn't need cut/sed or any such crude tool for the configuration files either, you could have a universal conf-edit tool, that could read the raw config files and output the configuration in whatever formal (XML, JSON etc) and convert it back in, search for specific entries, set specific settings, etc.
>Others yet require rich object configuration specifications, in which case JSON/TOML/YAML makes sense. I don't think there can be one configuration file to rule them all.
Even so, there can be one configuration language for an awful lot of programs, that don't have those special needs, and there isn't one. Instead it's a mishmash of every kind of custom parser.