We think that people in the real world do not use the smoothing options at all and checking for their impact revealed that they seem to have no effect at all in most cases. We decided to remove the options from the preferences. In addition, there's a message in the terminal when no smoothed mesh could be created which is the case for some single-slice segmentations. It even suggests to try again without smoothing. However, this should probably be a more prominent feedback as message box for example.

I tested this and the smoothing works but as stated in the description it should be made more obvious what to do.
As @kislinsk wrote we will not tackle this issue here but instead remove the options from the preferences. However, this is more about the context menu action "Create smoothed polygon model". Should the whole action be removed? Or are we only talking about the additional preferences for "Smoothed surface creation"? If only the preferences should be removed we still need to adapt the checklist to make it more clear how a smoothed polygon should be created.

Maybe the comment should was mistakenly added here and should have been added to T28793: [Segmentation][Multilabel][Options] Changing only decimation rate has no visible effect in "Create smoothed polygon model"?

We discussed this and we decided to remove the options from the preferences completely. This will be done in the mentioned task T28793: [Segmentation][Multilabel][Options] Changing only decimation rate has no visible effect in "Create smoothed polygon model".

For this task I clarified the description of the "Create Smoothed Polygon Model" section inside the Segmentation Options checklist.