We humans are very visually stimulated.
Something that is seen tends to grab our attention. This is why companies create unique logos and have commercials that grab your attention.
Radio marketing can be effective—hearing testimonies, etc.—however it falls short of displaying a product. It has no visual component.
You want to choose the vehicle that best communicates your message and accomplishes your marketing objective. For many audiences, products, and services, that will involve visual marketing.
