It's an old saying that customers don't need drills, they need holes.
Simply put, we buy products to increase our personal satisfaction - by either improving the positive or eliminating the negative. So, we know what we want, but may have difficulty expressing it to companies.
A good job description consists of three key elements:
1. An overall description of the role.
2. A defined set of responsibilities
3. A clear set of experiences or qualifications.
Sounds like what we should publish for products.
For a good description this topic see "Finding the Right Job for Your Product" in MIT Sloan Management Review, Spring 2007.