Why?

The only it does to handle PHP 5.3 by using FormatJson otherwise it outputs the array with json_encode.

```
	/**
	 * @note JSON_PRETTY_PRINT, JSON_UNESCAPED_SLASHES, and
	 * JSON_UNESCAPED_UNICOD were only added with 5.4
	 */
	public function encodeJson( array $input ) {

		if ( defined( 'JSON_PRETTY_PRINT' ) ) {
			return json_encode( $input, JSON_PRETTY_PRINT | JSON_UNESCAPED_SLASHES | JSON_UNESCAPED_UNICODE );
		}

		return FormatJson::encode( $input, true );
	}
```