One of the first things I learned in Interactive Media was that I should design thinking of metaphors so users could understand immediately the use of a digital tool. For instance, in the “desktop”, the tool to get rid of unwanted “files” looks exactly as the bin. It is not a real bin that you can accidentally touch dodgy sticky things. It is a virtual representation. However, if this virtual bin looked like a triangle, it would’ve been much harder to explain the new users that dragging and dropping something onto the triangle it would make the object disappear. Now, imagine that every element of the desktop was a shape instead of a real object. It looks like a mess, doesn’t it? What is the circle? What is the square? And they are all floating in 3D! Think of all the possibilities.
Furthermore, if this metaphor is not used properly, it can make the users even more confused. For instance, a button affords to be pushed and trigger some interaction. A person wouldn’t spin a pushable button, so don’t create an interaction with a spinnable button. No one will understand and consequently feel frustrated.
Moreover, a kid nowadays wouldn’t understand why it is necessary to click on a floppy disc to save something. They have never used a floppy disk. Do they know what it is at all? Thinking of icons is not as easy as it looks.
This formula has worked very well for the past 20 years more or less. So much so, a design philosophy dominated the UI design field fuelled by Apple’s success: skeuomorphism. That is the extreme copy of a real object: the more real it looks, the better. Virtual calendars have leather texture and bits of ripped paper. The button looks so real, it shines when it is tilted.
However, UI designers got tired of it and they started to question if users still needed these clues. They wanted to have the freedom to abstract. That is when flat design got strength. It is almost a complete negation of skeuomorphism, as most trends are an antithesis of the previous one. Of course, metaphors and affordances are still best practice, but they are not taken to the extreme. Minimalism with blocks of colours and beautiful typography seems to be the new norm.
