Of course, this would require you to take the extra effort to implement the needed renderer. But once it is implemented, it can be shared with other people.
Regarding configuration syntax, Yii mainly uses one single application configuration file. Because it is a PHP file, we can implement some special configuration reader and return it as the needed array. Like the above renderer, this also needs the effort to implement the needed configuration reader, but it can also be easily shared with other people once implemented.
Since different people really have different tastes, we think it would be better for the framework to keep the core simple while leaving enough flexibility to allow plugging in extra capabilities.