Description of problem: So far it is noticed that $subject can only be configured if a workspace applet is added to gnome-panel, with the recent addition of compbiz it seems that workspace applet is not always required. In a situation where workspace applet is not used, but the workspace preferences need to be adapted that requires adding the workspace applet first. I feel it will be a good idea to add this preference option to gnome-prefernece menues.
hmm, changing the number of available workspaces seems like a fairly rarely used operation right? Just to be clear, you're asking that the workspace switcher preferences dialog be separated from the workspace switcher and be available from System > Preferences? I don't think that's something I'm going to be working on in the near future, so I'm going to go ahead and close this bug out. Feel free to file an upstream bug report at http://bugzilla.gnome.org. If your request gets implemented will just pull in the changes. If you do file upstream, please make a not of the upstream bug on this report.