I am a management consultant who specializes in the four areas of Strategic Simplicity®: change simplicity, market simplicity, decision simplicity, and user simplicity.
How important is user simplicity / design, especially with software?
It can change an entire corporate strategy.
I consulted and worked for a large multinational bank that developed an IT strategy to develop it's own web portal—which would eventually serve as the user interface for all of its legacy applications. They even hired away some key executives from a prominent travel website, who were responsible for the travel site's state of the art portal design.
Around the same time, this bank entered the Chicago area and bought a local bank 1/10 its size. The larger bank expected to shut down the smaller bank's technology group and move customers to it's platform.
It turned out that the small local bank's software was rated much higher than the larger bank's in a survey conducted by a prominent banking magazine. Their user interface was so good that the larger bank had to do an about-face with its strategy.
They ended up scrapping plans for its own portal, and they ended up shutting down the larger bank's software and switching to the smaller bank's platform. The newly hired key portal executives ended up leaving, and the smaller bank's technology executives (who thought they would lose their jobs) ended up running the larger bank's tech operations.