How easy is it for us to say what we really want?
If you ever go to your customers and ask them what features they want in the next release of your application, you absolutely must read this post: UX Myth #21 - People can tell you what they want.
Even now, after so many research reports, articles and books describing how many companies got things wrong by thinking they could simply ask customers what they wanted, we still seem to fall into the trap of thinking all we need to do is get a bunch of customers in a room for a day and then pepper them with questions about what they would like to see in the next version of their phone, app, etc.
It just doesn't work that easily. You need to know how to ask good questions and even more, how to be a great listener and understand what customers are telling you. You need to observe them actually using the current version of the product, since what people tell you they do and what people actually do are often quite different.
Just don't think that you've done good customer research by asking customer what they want. They won't be able to tell you.