You can save on time. The directors manage the company. Instead of directing the company yourself you can find someone suitable so that you can have more time to do other important things.
A professional director can monitor more closely. You might not be able to run your business from afar and a professional director closer to the activities can help.
A professional director can bring expertise. Some businesses are specialised and require special skills and knowhow, and a professional director with the required experience and can be the solution.
You can have some added privacy. Sometimes people think the business is owned by the directors because the directors are the most visible persons in the business. They are the ones who sign contracts and other agreements, and who execute transactions. They open bank accounts, sign cheques, promote the company and answer questions.