Bridge capabilities help the system determine what kind of bridging resource is best suited to host your meeting. If the wrong kind of bridging resource is chosen, some kinds of endpoint will not be able to attend your meeting, or you may wind up wasting a valuable, expensive resource hosting a meeting that would be just fine with a cheaper resource.

However, the system does have some intelligence to determine the correct bridging resource without any bridge capabilities being specified. So, strictly speaking, they can be left empty. However, this kind of inference only works with provisioned endpoints, so if you have either unprovisioned or remote endpoints in the meeting, you probably want to explicitly set bridge capabilities.

To summarize, it is OK to omit bridge capabilities:
- When your meeting contains only provisioned endpoints and you trust the inference algorithm
 
You should probably NOT omit bridge capabilities:
- If any of the endpoints in your meeting are unprovisioned or remote endpoints.
- If you need to override the inference algorithm, for instance you want a more expensive bridge for some reason even if the supplied endpoints would work with a cheaper bridge.
 
You CANNOT omit bridge capabilities:
- If your meeting contains no provisioned endpoints, as there is nothing to infer.