Softness of light come from the size of the light source. eg, sunny day you have harsh shadows, cloudy day you have soft shadows.
Omnibounce work best in a small enclosure areas, with walls and ceiling, same as LS PJ or bounce card.
If the subject is 20'~30' away from you, there is not much difference between a 1.5"x2.5" and a 2"x3" or a 4x6 light source in a open area, only wasting flash power.