“Simplicity is the ultimate sophistication,” wrote Leonardo Da Vinci. He would paint over work that didn’t meet up with his expectations. Not surprisingly, Steve Jobs adopted da Vinci’s maxim in designing Apple computers.
Simplicity is the reduction of complexity. It unclutters the multiplicity of crayons and fence-sitting gray space in the middle and replaces objects with mere black and white.
Simplicity comes from revision
Simplicity retains the essence and deletes the rest. Take a look at the sequence of Picasso’s drawing of a bull. He pairs down the bull from full detail down to its fundamental shape.
The simplicity of design directly relates to the clarity of design — retained and kept implicit is the main thing that gets featured in the work.

Only when we remove the excess can we appreciate the beauty of simplicity. What results only appears natural because all the explaining was wiped our during reduction.
The experts know what to ignore.