There's no better way to market your company or to add some "pow!" to your credibility than to have your satisfied customers do the work for you.  When you give these happy customers the power to make a difference in your business, they automatically become more emotionally invested in the relationship and your company's success.  Everyone likes to know that their voice has been heard and that they have made a positive impact, so why wouldn't you capitalize on your biggest marketing asset- your current customers- by empowering them to help you to be better and to earn more business?