StaticBatchingUtility.Combine sets up static batching for several objects at runtime. It offers the following advantages over marking objects as batching static in the editor:

-Allows the performance advantages of static batching to be applied to objects generated at runtime. Since such objects don't exist in the editor, it's not possible to mark them as batching static.

-Objects setup to be statically batched in this way can be moved by adjusting the transform of their associated staticBatchingRoot gameobject. This is useful for sets of objects that move together as a whole.

For these reasons exposing StaticBatchingUtility.Combine would provide world creators with a useful tool for optimizing their worlds.