My high regard for customer affinity is one the main reasons why I'm such a fan of Extreme Programming and other agile methods. I found it very significant that when Kent Beck summarized XP to his agile peers at the snowbird workshop which coined 'agile', he chose to describe not the technical elements of XP, but his desire to change the nature of the customer/developer interaction.

I've often heard this relationship mis-characterized. In particular there is a belief in some quarters that the customer team just comes up with stories which they throw at the developers. This characterization is rather like the notion that requirements are just lying out there to be gathered. Either way that's not much of a collaboration. Instead developers need to work together with domain people to generate ideas with developers learning a lot about the business in the process.

One of Kent's suggested names for 'Agile' was conversational software development - the point being that it's a two way communication. This isn't something like a telecoms protocol that you can define, but the back and forth discussions about how software can enhance the business are where the real value lives. Much of this conversation is of half-baked ideas, some of which grow into valuable features - often ones that aren't things that the customer originally thought of.

Martin Fowler, Customer Affinity