It would be a tremendous benefit for all Modeling users with the effort to grow towards PLM with Windchill, if the PTC Creo Elements/Direct Modeling integration to PTC Windchill via the Workgroup Manager would be capable to open "none native CAD files" from the workspace like e.g. the Creo users can do it today. Please see the below comparison of the 2 different File open dialogs. In the PTC Creo Elements/Direct Modeling dialog only Modeling related files can be displayed, where as in the Creo App's Parametric and Direct, the all file types toggle is available. Both screenshots view the same Workspace.
View of a Workspace for a PCT Creo Elements/Direct Modeling user:
Only the Modelling related files are available.
The same Workspace for a Creo Parametric & Direct user, All Files are available: