I design video games. I don't want to get into the minutia of my job, but at the end of the day what I do is fundamentally about engineering systems for people to interact with. You may not think much of that, but I spend at minimum forty hours every week focusing on how human beings interact with things and designing systems based around that. I'm not an idiot or ignorant when it comes to this so I really do not appreciate being treated as though I am. I've designed games which have sold millions of copies, so apparently someone thinks I'm good at designing interfaces (which is what instruments, especially keyboards, are). I'm willing to bet that I've read more books on general design than you've ever heard of. I don't say this because I think I'm so special, but because I am being talked to like a child.
I had to play the piano for years in music school and I had to do so well enough to pass the classes, which was not amazing but also not a trivial level of ability.
If you want to tell me that the modern standard keyboard is not designed around C Major and it's modes, then I don't know what to tell you. That's simply how it is.
Everything has flaws. Every design, from something as simple as a door, has flaws. For example, most doors open one way. That's a design flaw. It's more intuitive in one direction than the either. I could even point out numerous flaws in the keyboard I am typing on right now. There are significantly better layouts that are possible, where the hands will naturally alternate more often based on the most common sequences of letters in the English language. We use this one because it achieved standardization first, but it is actually not a great key layout.
This is very similar to the piano, or even western notation as a whole. The whole system is based around C Major and it's modes, with everything else being treated as abnormal. This is especially true once you leave the modes of the C major scale and move on to more alternative scales. They become increasingly unwieldy and awkward the farther they get from the classic scales. This is a problem that you may notice simply doesn't exist on many instruments, most notably for this discussion, bass.
All 12 notes are an equal distance, relatively, from the one before and the one after it. Having certain notes represented by smaller black keys, as opposed to larger white ones, is FUNDAMENTALLY unintuitive, because it treats things which are identical in relevance as totally different.
If I designed a typing keyboard where the less popular notes were on smaller keys, it would be derided as quite horribly designed, because a single size is significantly more intuitive to the use of your fingers.
Schoenberg had the same opinions as I do about the emphasis of western notation on C Major, so if you want to tell me that he was a moron who was totally wrong and didn't know what he was talking about, and never learned how to play music, well you are entitled to your own opinion, even though you clearly don't think I am.
I recommend the books The Design of Everyday Things, The Art of Human-Computer Interface Design, The Humane Interface, and Universal Principles of Design if you want to learn about the subject of how humans interact with things.