listen up

So I was watching this interesting video on the importance of interaction design in products. (found via forty)
In the video they had this sketch.

Here they are describing the process a customer takes as a relationship.
So the M is marketing. Getting the customer to the point of purchase (P). The area after that is the Interaction Design. Most businesses and organizations focus on the M.
So here is where the illustration / video left off. Why is interaction design important? The customer already paid right, so who cares. Wrong. Great interaction design, will feed the marketing side. Look at products with good interaction design, in relation to their marketing.
Examples that come to mind for me: Apple, Nintendo WII, In-n-Out Burgers, and toyota Prius. All barely have to market at all. They have created such a great user experience or product, that word of mouth marketing is free and in abundance.
So the moral of my story (as it often is), Focus on your end product, the interaction design, the customers experience, and the marketing will be cheap(er) and easy.