I just checked. Wings 1.2 does indeed write out smoothing groups when exporting OBJ files. I know when I started using Wings, it didn't do that, causing some grief.

Of course since smoothing groups are defined in terms of polygons, not edges, Wings can only create smoothing groups for regions that are completely enclosed by hard edges. If one, for example, makes a cube and defines a single edge as hard, that information will be lost on export.

-- I'm not mad at you, just Westphalian.