Packaging is very cheap, it is usually in the lower half of the dollar. However it does protect the product when shipped. Unless you know a local manufacturer that you can just pick up the product unpackaged it still needs to be protected. Packaging it correctly does have its inherent advantages.
Let say you have no idea of the product and walk down the distributor's aisles, if you have something that catches the eye than it makes the biggest difference in the world.
Or even the sales counter people who walk by it everyday at work, they will notice it enough on the design to have it in their head when customers ask for a recommendation.