It's about time we start seeing more physicality in our user interfaces!
We can make things look convincingly like glass, or metal, or even materials that don't exist in reality. One reason for flat design is because it was the lowest common denominator and easy for devs to implement. If Apple makes it easy to implement this liquid glass stuff - Rectangle().background(.glass) or something - then it's going to be really successful.
The 3D buttons in Windows 98 (Start button, for example) must have be harder to develop due to the animation involved. Yet, that was perfectly fine on hardware much older than those on which flat UIs were developed. I think you are missing the main point, which is that designers maul designs every season exactly like in the fashion industry due to merely being employed to do so and feeling a need to produce something new all the time (, which is sub-optimal for the humans who have to bear the UX consequences, to say the least).
"Slowly, I'm coming to the conclusion that designers should never be employed, only consulted on a per-project basis. If they sit around 8 hours a day, they end up changing something or the other to justify their existence. But human beings are not used to change at such a rapid cadence. Humans take time to settle into a design and establish patterns of usage."
How many designer friends do you have? Do you know what they do daily? We know your preconception that regardless of company size and product they are just counting beans.
Can you please tell me your thoughts on how it is "hard to defend"?
My thoughts: How can designers criticize the use of Comic Sans? If users use it where it's connotations (childlike, casual) are appropriate, such as birthday parties, and love it, who are designers to comment on it? I find this indefensible, as if design sensibilities have a foundation very much like mathematics or physics and there is a clearly Universal litmus test of good design and bad design. There isn't. In fact, arbitrary mores of fashion such as "Comic Sans is uncool" are the very tell that design has foundations as strong as a piece of string in the wind. The disdain for Comic Sans reeks of elitism, where designers gatekeep "good taste" based on arbitrary conventions.
A burning need to dominate in a misguided attempt to fill the gaping void inside
Broken and hurting people spreading their pain as they flail blindly for relief
Our world creaks, cracks splintering out like spider thread
The foundations tremble
Researchers in chemistry and biology may enjoy a similar joy, but I assume it is much more difficult to re-run your experiment with slightly different ingredients. One aspect where these fields are leaps ahead of code is "code producing code": chain reactions are common in the real world and in fact, probably key to the whole thing.