The problem with Ford's quote is that the customer offers a solution. In such a case you need to ask further questions to find out the problem he wants to solve. Had Henry Ford realized that, he would have found out customers wanted to get from A to B faster and he wouldn't have quipped this silly 'they want a faster Horse'. They didn't actually want a faster horse. As soon as you understand the problem, you're free to come up with innovative solutions.

There are still a few exceptions though: you can create a new market by appealing to a need people didn't have until you offered a solution. Fashion, fads (including fads for children), arguably Twitter,...