The first time digital interfaces came into existence, designs were quite basic. Straight lines, simple shapes and text. But soon after that, with higher resolution displays and faster GPUs the possibilities became endless.
The earliest designs in digital GUIs resembled a much of real world objects. Skeuomorphic design aims to emulate the aesthetics of physical design. This type of design was very common in the early designs at Apple. That eventually changed to a more digital-first design, also known as the flat design.
Skeuomorphic design is common in digital plugins in the audio production domain. Knobs and meters resemble the actual physical instrument.
The best user interface is the one that no one notices. It should just melt away in it’s function. It should get out of the way rather than pose as a hurdle to cross to achieve something. Reducing the number of clicks for each operation is a good start. Making the response time really fast (sub 100ms) also helps. But these are just tricks. What really matters is the overall concept. The concept of what needs to be shown and what can be hidden. What is really necessary for the user?. What can be defaulted or figured out in some other smart way? Visibility is key. Whatever is shown on the screen should be easily understood and discernible. Unlike the new Google icons. Colors convey a mood. A combination of colours and movement can convey an emotion.