MarFarMa/wp-cli — comment on commit dcc129348e11efdf14d0630ce9aa53daa019d2fa
File:  line 0
By scribu:

> It's human editable. Serialized options can be easily modified, with the migration/import function re-packaging the values as needed.

So is PHP code, which is what `var_export()` produces.

> And a YAML file can contain PHP code that is evaluated just before parsing. I'm not sure that I'll need that feature immediately -- but I like having the option.

See above.