It is useful because users can select a folder to export with IronPython without installing API on the server.
Now if you use the FolderBrowserDialog() in Spotfire Analyst (Windows) it works, while in Spotfire web client does not work. It reports "Showing a modal dialog box or form when the application is not running in UserInteractive mode is not a valid operation. Specify the ServiceNotification or DefaultDesktopOnly style to display a notification from a service application."
This is a general limitation with any web application (that runs in a standard web browser).