It's true that people are more creative in private than they are in public. But, that is why brainstorming sessions are so useful.
Brainstorm sessions might surface creativity that has already happened. If you ask a group, "What are some product ideas we haven't considered?", there's a chance that some people have been independently thinking about new products, but wouldn't have thought to propose them.
Or they can serve to direct/request creativity. If you ask "What are some product ideas we haven't considered?", people who had not been thinking about new products, might start. It gives them something to think about on the drive home or in the shower. I've received some great ideas via email a few days after the actual session.
Brainstorm sessions might surface creativity that has already happened. If you ask a group, "What are some product ideas we haven't considered?", there's a chance that some people have been independently thinking about new products, but wouldn't have thought to propose them.
Or they can serve to direct/request creativity. If you ask "What are some product ideas we haven't considered?", people who had not been thinking about new products, might start. It gives them something to think about on the drive home or in the shower. I've received some great ideas via email a few days after the actual session.