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This question involves consideration of two sets of variables, experience and users. In turn, the experience variable involves at least two perspectives, general and specific. Compared to defining requirements for the latest upgrade to an existing product line, it must have been a far different world at Apple defining requirements for the first iPhone.
Imagine defining requirements for a truly breakthrough product, before anyone had ever been exposed to its various forms of usage and functionality. You couldn't just ask a couple of prospective users what they want, because they have no context. Henry Ford supposedly said about what eventually became mass-produced automobiles that today we take for granted, "If I had asked people what they wanted, they would have said faster horses." One of Ford's most important requirements turned out to have nothing to do with vehicles. Rather, he led the way to dramatically increase worker salaries so the workers could afford to buy his cars.
Similarly, when Xerox was inventing the first photocopier, people saw no requirement for it. Prospective users were accustomed to carbon paper and could not conceive of needing anything else. The machines caught on only after Xerox placed them on free trials in offices. By the time the trial ended, people wouldn't give back the copiers. They had become hooked on using the machines to satisfy previously unidentified requirements that they'd actually had all along.
Of course, many mobile application requirements are outgrowths of related experiences, such as using graphical user interface computers. Before the iPad was a progression of increasingly graphically driven Apple computers and their counterparts using competing operating systems, such as Windows. Few people remember that Xerox actually invented the concept but couldn't make it succeed financially; and neither could Apple with its first effort.
Innovators have to "invent" user experience requirements by thinking on behalf of potential users. They need to identify a set of likely key user types/classes/personas and become intimately familiar with what they do, and especially how they do it and what they think about it. Innovators have to put themselves in the place of actual prospective users, who at that point, cannot identify their requirements for using something they cannot conceive of.
The secret to doing it well is focusing on the essence of what the users are trying to accomplish to achieve value and not being distracted by trying to design the features of the product or app they intend to build. For innovation, user experience requirements relate to identifying and overcoming things that interfere with a user's ability to do what's needed to achieve value. Once functionality, user experience and other requirements have been identified, the next challenge is designing product features that satisfy the requirements. This is what business analysis should be. It's not new or limited to mobile apps.
Initial innovation perhaps is now less of an issue for Ford, Xerox and Apple, but user experience requirements remain a major competitive concern. Once a concept becomes established, actual users' experiences are a more dominant source of related requirements. Innovative invention is still a part of defining user experience requirements, but incremental reaction to actual experience often is the larger source. That can be good in the short term but ultimately can prove limiting as it becomes harder to excite customers about upgrading to the latest release that looks pretty much like the prior ones.
This is where the user side becomes the basis for innovation. That is, the next form of innovation is inventing new usages and experience requirements for users. For example, nowadays cars seem to be advertised pretty much as mobile devices and copiers are now getting supplanted by, among other things, mobile phone photo apps.