I only use one workspace, but I don't know how to reduce it to one.
That being said, I would like to know how I can change the "Workspace Switcher" behavior. I'd like to see the same thing as I see when I press Super+ W, when I click on it.
The behaviour of the Workspace switcher launcher is hardcorded into Unity and you can't change it unless you try modifying the source of Unity.
If you want, you can create a new launcher item that lets you use Windows spread by following the answer in this question.
And, you can try changing the number of workspaces by following this question: