How about, in addition to the negative reasons you listed, you include the idea that for a substantial portion of humanity math is hard. That doesn’t mean it can’t be mastered, and I’ve known some people who had little talent in math who, through hard work, acquired advanced math skills. However, many people who find math hard avoid except when necessary because they don’t find it fun or enjoyable.
Thus, when writing a book geared for the general public, if you include math you’re likely to make it less appealing to those who dislike math not through stupidity or laziness or “too cool for school” but rather because they find it hard. It’s one thing to exert the effort because your job requires it, or your life requires it, it’s quite another to expect people to do that for what is intended to be a popular book.
As an analogy, I have on occasion run a mile, but I detest running, I don’t enjoy it, and avoid doing it unless there is some underlying motivation. That motivation might “required to pass the gym course” or “Someone will pay me $100 to do this” or “someone is shooting a gun at me”, but it’s not something I’d ever do for fun. I don’t enjoy hot weather, either - I’ll work outside in hot weather for eight hours or longer if I’m getting paid to do so but unless you pay me I’m sitting indoors, in air conditioning, sipping a cool drink. I don’t run for fun, I don’t sit in hot weather for fun, and I don’t do math for fun.
I learned what math I actually needed to know, then some beyond that. I had to learn some additional formulas when I earned my pilot’s license, which I did, and committed to memory, and became quite good at them, but if it wasn’t for the fact that a hobby required that knowledge I never would have bothered to acquire it. For me, math is a strictly utilitarian subject. I only bother to learn what I actually need to know, because I just don’t like it.
I read Stephen Hawking’s book. I didn’t run screaming from the room when an equation appeared on the page. Then again, he did make an effort to explain as much as possible without math equations, and what was included was rather important to understanding what he was talking about. I found the subject sufficiently intriguing to wade through that. That’s all.
Bottom line, I hate math because I find it hideously difficult to master (though I did exert the effort to get what I need to get by in life) and in no way find it enjoyable or pleasant, although sometimes the results of math are sufficiently appealing so as to induce me to exert the effort to learn/perform math operations.