Sometimes we need to set an edge hard even though it doesnt qualify in an acute angle. I would be nice if as the same way it is a button under the Edit Edges panel saying: "Display Hard Edges" there would be other saying: "Select Hard Edges".
I dont think it is necessarily hard to implement since it shows already in green the hard edges.
It would be time saving to have them selected for uv unwrapping since the option Flatten by Smoothing Groups doesnt break apart hard edges not delimiting an specific area.