Hovering onto the workspace icon while dragging a tab would open that workspace and let you put your tab in there.
This feature would be analogous to dragging tabs between the windows.
Or, the different approach could be dragging and dropping a tab onto the workspace icon would put the tab in the workspace.
Now, transfering tabs between workspaces is tedious, because you have to put all tabs into the new window and drag them into the desired workspace. This feature would make transfering tabs alot easier