Multiple authors (Sabrina, David, Stephen) have stated that either the "Create Smoothed Polygon" option does not work or works but is no different from the "Create Polygon Model" result.
I think this is more an issue of stating clearly in the checklist that multiple segmentation masks should be created in neighboring slices to get a clear difference between the "Create Polygon Model" and "Create Smoothed Polygon Model". If only a single segmentation mask is created then the Create Smoothed Polygon does seem to fail.
Steps to reproduce:
1) Load 3D image.
2) Create segmentation for the image.
3) Draw segmentation masks in neighboring slices in a view. (if only a single mask is drawn then "create smoothed polygon model" is no different for "create polygon model"
4) Right click on the segmentation node in the data manager and click on "Create Smoothed Polygon Model"
5) A smoothed polygon should be created in the 3D display view.