Here are some of the benefits you get:
Bake Radiosity changes Adaptive Subdivision result into new Mesh object. Furthermore, the lighting calculation result are baked on these vertices. The GI effect can be given to walk-through and real time viewing with Nitrous feature. It can use for background data creation of GAME or Design Visualization preview, etc.
Situations in which you would want to use BakeRadiosity:
Background Stage Model creation. Real-time Design Visualization Contents creation.