I say 'fix' as it is more of a work around, basically un-welding hard edges, but it gives the same end result.
Not sure why you think that functionality is new in the last few days, because that has been an option for the last few years (probably before this thread was started.) Perhaps the interface for doing it has changed so it seems new? Like, you weren't selecting edges directly, but rather welding/unwelding polygons.
The issue wasn't that this couldn't be done within UU, but that there wasn't a way to define smoothing groups within Maya. This is addressed in the latest version of UU because there is now an exporter for Maya.