I've worked with several product managers who never really grasped the concept of a minimum viable product (MVP). They often over engineered user interfaces or added features the customer never wanted or used.
It usually took one failed product before they caught on and started asking me how this MVP thing works.
It's all about creating learning loops with your customers.
Chris Bank pens this brilliant article -- Building Minimum Viable Products at Spotify.
So good, everyone on an Agile team should read it twice. We learn about Spotify's 4-stage iterative product cycle.
The four stages combine practices from Lean Startup and Agile. Keep reading the article and you'll learn the Cupcake Model of product development.