There are several reasons why it may be advisable to purchase cargo insurance in addition to your business' existing commercial insurance:

1. Cargo insurance specifically covers the loss of, or damage to, goods being transported, while commercial insurance may not. While commercial insurance may provide some coverage for goods in transit, it may not be specifically designed to cover the risks associated with transporting goods.
2. Cargo insurance can provide coverage for a wider range of risks. Cargo insurance policies may offer coverage for a wider range of perils than commercial insurance policies, including accidental loss or damage, theft, and other risks that may not be covered under a commercial insurance policy.
3. Cargo insurance can be customized to meet your specific needs and scale with your business, allowing you to tailor the coverage to fit your unique risks and exposures.
4. Cargo insurance can provide peace of mind. By purchasing cargo insurance, you can have the peace of mind that comes with knowing that your goods are protected against loss or damage during transit.

Ultimately, the decision whether to purchase cargo insurance will depend on the specific needs and risks of your business. It may be worthwhile to consult with a licensed insurance broker or agent to determine the most appropriate coverage for your business.