It's also important to remember that customers will tell you they want features they they won't actually use or pay for. So it's necessary to develop an understanding of what your customers do and what problems they're trying to solve.
This often helps more than just listening to features they say they want. If your customers aren't in the business of building products (especially software products), their ability to ask for features is limited by the fact that if you're not an expert in how the product is created, it is difficult or impossible to know what features might be easy to add, and which ones are difficult.
It's even likely that you can add features that your customers that your customers don't even know are possible. In this case, they won't be able to ask for those features, or anything like them. As an expert (in software, or any other specialized product development field), taking the time to really understand your customers, the problems they face, and the jobs they are trying to accomplish can help you come up with new features and products that actually amaze your your customers and attract new ones.