If you encounter the “Unrecognized attribute ‘allowInsecureTransport…” error when you want to display the properties of a SharePoint 2010 Application Service (like the “Managed Metadata Service”), it is likely that it is a known issue of the WCF framework.

Microsoft has just published few days ago the hotfix KB976462 available on the connect site that solves the issue and enables the edition of the Application Services properties.