You probably sell your products mainly on an individual basis. Yet, if you group different products together and sell them as a single entity, you create "new" products. You usually do not need engineering or manufacturing to help you create them, just marketing. The major advantage of packaging is that you transform products without unique strengths into products with unique strengths.
Example
Home Depot sells assorted toolboxes and tools on an individual basis. Occasionally, they package selected tools with a toolbox as a new Handyman special product. The tool and toolbox selection will vary with the level of expertise of the targeted customer (weekend warrior or professional). The price of the package is less than if you purchased the tools and toolbox separately.
Home Depot made a competitive product with unique strengths out of commodity items.