If people don’t know what they like, how do we make things that they will like? [duplicate]

Possible Duplicate:
How to discover what users NEED and not what they WANT?

The question "What are your favorite counter-intuitive principles or ideas within UX?" has interesting responses from DA

One I like is Steve Jobs' opinion of focus groups. "It's really hard to design products by focus groups. A lot of times, people don't know what they want until you show it to them.").

and Leah

The Steve Jobs comment reminds me of Henry Ford quote “If I had asked people what they wanted, they would have said faster horses.”

If we can't always ask people what they like, the challenge is to make things that they will like even if some forms of research don't back our ideas up.

Jakob Nielsen suggested here

To design an easy-to-use interface, pay attention to what users do, not what they say. Self-reported claims are unreliable, as are user speculations about future behavior

What can you add to Nielsen's suggestions? Observing people instead of listening to them is a good way of gathering data. However, this doesn't seem to be enough for Henry Ford to figure out that faster horses isn't the solution.