One of the biggest mistakes made in startups is asking people what they want. It’s not uncommon I see startups only testing their products and services. While instead they should have been asking and researching the problems.
Your target audience is under constant influence. By the time you finally ship the working product someone asked for, their view on what they want has changed. Probably already found an alternative or solved the problems themselves.
Secondly people are really bad at predicting their own behavior. They know about their problems, but they can’t design the best solutions. They have ideas, but probably those are not suited for the mass market.
Designing working and marketable solutions for problems is your job. Not that of the people you talk to.
How the product is perceived is what you should measure when the product is being designed. But measuring how people like a solution is very different than asking how they want their problems solved.
Update: Check out this post from VentureHacks for a more in-depth look how Steve applied Customer Development.