Use case or problem
If the name of the active workspace (in practice, the workspace most recently opened) could be used as a variable in Bases, I think it would make Workspaces more convenient — for example, by making it easier to list related files for each workspace.
Example
filter: file.tags.contains(workspaces.active)
Current workaround (optional)
Create separate Base files or MOC files for each workspace and save them as part of the workspace.