That's why you need to read critically and not blindly trust the author. I personally think that anything can be understood infinitely well, everything has an explanation, everything has a reason, etc. Hence, if the author would say that, I wouldn't believe him.
Actually, I don't think everything has a good intuitive explanation. No one seems to understand the classification of finite simple groups. The proof evidently consists of thousands of pages. In principle, maybe it's understandable in the sense that if you had an unlimited amount of time, maybe you could understand it. But I'm not sure about that. It's hard to think of other good examples right now, but there are limits to human understanding. Some things that have been shown to be true might not really be understandable. But in that case, there's no point in learning the proof, unless you are actually in doubt as to the veracity of the statement and wish to check it for yourself. But from a learning point of view, it's a waste of time.
But you have the right attitude, there. Usually my reaction IS to be optimistic, but not unrealistically optimistic about being able to understand things deeply. So, if an author presents things in a way that seems too opaque, my warning signals will flash very strongly and if I can't figure out a better explanation myself, I'll keep looking until I have looked at every available book that covers the material. And if that doesn't work, I'll keep thinking about it. I might set it aside even for years, but I never feel like I am done with my work until I have gotten to the bottom of it. There are many such things I will probably never get to the bottom of, though.
Also, there are times when even I think too formally, and I just don't know that I'm doing it. It happens to me, and I'm sure it happens to everyone else. The risk of that happening is much, much greater if the books you read are too formal.
This is true. However, as I mentioned before, the intuition you found yourself, you've built yourself is even stronger, even more natural to you. The very act of building intuition, building mental models improves the ability to do it, which is the most important thing when learning mathematics, at least in my current point of view.
You can get plenty of practice building your own intuition without spending all your time decoding it from formal proofs. You can prove your own theorems, even. I don't really think it matters whether you come up with it yourself or someone tells you it, as far as understanding the particular thing they are trying to tell you. As far as getting practice, yes, it's better practice to come up with it yourself. But that's a different goal than just trying to learn such and such proof or definition or whatever specific thing it is. Often, you can do a better job than what you are told, but if whoever was telling you did a better job from the beginning, the effect would be the same. Still, of course, you are a different person from them, so you have to think about it critically. Just because they don't force you to decode their formal proof doesn't mean you just sit back and expect to learn it automatically. You still have to mull it over for yourself until it's clear. Maybe they have more intuition built up than you do, so you have to spend more time filling in the gaps that they didn't tell you.
No, that doesn't mean that all books and teachers are good. But only the fact that YOU don't like a particular book doesn't make that book a bad one.
The fact that a particular book didn't take human psychology into account DOES make it a bad book, though.
By saying for humans, you mean for YOU really. So what you are trying to say is, if you can't write for me, then don't write at all! No offence, but that's a terrible attitude. And yes, spending a lot of time choosing a book is crucial.
No, he doesn't mean himself. We evolved out there in the wild. We evolved to do things like hunt, socialize, cooperate, get away from danger, and so on. Writing wasn't even invented until relatively recently in our species history. So, it's no surprise our brain deals better with things that we call "intuitive", like pictures, pushes and pulls, sense of motion and touch. Our brain evolved to process that kind of information, not symbols. It's just foolish not to take full advantage of that and to communicate with that in mind.
Once again, if YOU don't understand it, that doesn't mean that nobody understands it. Some people just might enjoy reading formally written books (my own personal taste asks for a little bit of intuition too though).
It's not just about whether you understand it or not. I can read math better than 99% of the population, including formal math books. But just because I was able to tease the intuition out of it after 100 times as much effort as it COULD have taken doesn't mean that it was well-written. The bottom line is that this type of thing is going to have a negative impact on the efficiency with which people can learn the stuff. And there's a great risk that the quality of understanding will also be compromised as well.
No offence, but it seems you base your judgments on your own emotions.
You too.
Objectively speaking, I have a good reason to believe that the continued over-use of excessively formal books will have a negative impact on how much and how well people will be able to learn, not to mention their enjoyment. I mean, having the experience of reading two books and having one make complete sense and the other wasting your time is pretty good evidence that one book was better than the other at least for you, and the reasons that was the case are reasons that seem to apply to other people, as I mentioned.
Emotion may be part of the point, actually. Why am I a mathematician? Is it because I love boredom? Is it because I am a masochist? No! I want to be entertained when I learn math. That's the reason I do it, and it has the potential to entertain if explained properly. So, regardless of what the "right" way to do it is, my goal is being thwarted.