Certainly an interesting perspective on a very pervasive problem. I saw the provocative question "Why Aren’t Math Textbooks More Straightforward?" on Quora just the other day. I take much the same view as you (though I religiously read not only my assigned math texts for classes, but also read their competitors in search of increased clarity and beauty.) I spent a few minutes writing up a few thoughts on what is going on in math textbooks taking a broader view of the forest instead of complaining about the trees.

Perhaps some of the tentative will gain a better appreciation for mathematics: http:/

The repetition that a good mathematician (or really any good thinker) reads books with a pencil in hand needs to be drilled down to younger learners.

A parting math textbook joke:

Q. Why did Nicolas Bourbaki quit writing mathematics textbooks?

A. "He" realized that Serge Lang was just one person.