"Graphical user interfaces are full of symbols. Symbols need to be reduced to their essence."
"Unless you are creating a virtual version of an actual physical object, the goal is not to make your user interface as realistic as possible. The goal is to add those details which help users identify what an element is, and how to interact with it, and to add no more than those details".
These are very good guide lines on the whole, and the author does make the point that while simplification is good, over simplifying designs can lead to obvious ambiguity. Keeping things simple enough is good, and backs up the mantra of "Don't make me think" used by usability gurus such as Steve Krug.
But is there something that we are missing here? What about good design, and what impact might design have on usability?
Studies have shown that identical functional designs can be perceived as easier or harder to use depending on how aesthetically pleasing a user interface is. The Israeli scientist Noam Tractinsky carried out a study using two ATM machines that were functionality identical, but one had a much more pleasing and attractive UI. To his surprise the results showed that subjects using the aesthetically pleasing design reported that they found this ATM easier to use. This effect is also known as the aesthetic usability effect.
Others such as Don Norman have also looked at how aesthetics in design impact our perceived usability. Norman states that there are three levels at play in design: visceral, behavioural and reflective. Visceral design is about how things look and feel, and is pretty much hard-wired into our brains. Visceral design is immediate, and is our first reaction to something. Aspects that make something viscerally appealing are, rounded soft edges, smooth surfaces, symmetry, primary colours etc..
Norman goes on to argue that not only does good visceral design give a perceived ease of use, but that it does actually make things easier to use. How could this be the case? The argument put forth is that using objects with good visceral design puts our brains into an open and creative way of thinking, therefore making it easier for us to solve small issues and ambiguities that we might find while using a device. While using UIs with bad visceral design puts our brains into a closed fight or flight mode, narrowing our thinking and therefore making these types of interface more difficult to use.
You may, or may not, buy into the idea that visceral design has an impact on usability, but lets take a look at a concrete example. Most would agree that Apples iPhone is a beautiful thing. But now lets imagine that we take away all the nice rounded corners, remove the reflective effects from the icons, even take out some of those nice transitional animations. It is still functionality the same, and you can still do all the things you could before. But do you think it would be as nice or as easy to use?
With all this in mind we can say that simplicity in design is indeed a good thing, but it should not be done to an extent that it affects the overall attractiveness and good aesthetics. So keep things simple, but do not neglect the visceral aspects of design. If you do, it could be that your product will be lacking not just in aesthetics, but also in usability.