I think it would be good if you could publish an app, and then add other versions to the same heading. For someone like me who wants to create different color themes in a watch face I have to publish multiple times. Another place where I think it could be useful though, is you could leave an older version available if there might be features or something that people preferred over the new version.
I realize that in the case of an app or widget you could handle most differences through menu choices. But you would not be able to have a "lite" version by disabling features.