In the modern market usability has become the most important quality criteria of software products. It is a more and more accepted fact that technology centers around the user and not the other way round.
Users must not be forced to adapt to technology. Instead the system's design must be natural and easy to understand for users.
In the foreseeable future software usability definitely will advance to the single most important criteria for success in the software market. Already by now users request more and more visually oriented and user-friendly software.
For modern software users the communication with the system -- that is the user interface -- is equally important or even more important than the internal workings of the software.