I teach college biology, and I've never seen a textbook in my discipline that wasn't written in a soporific and meandering style. Some are worse than others, but I've never seen a textbook I thought was good.

If I needed to fill a gap in my knowledge or learn a new subject I would never resort to a textbook until I had exhausted every other available option.

That may well be true in your discipline, but there are some excellent, concise texts in undergraduate mathematics. For example, Apostol's Calculus or Spivak's Calculus on Manifolds. Not the most accessible texts by a longshot, but not your average Pearson or Wiley drivel either.

Adding on to eigenvector's point, there's a certain beauty in a self-contained mathematics textbook.

likewise, the explanation for how the concepts flow together. drawing these connections is usually the last step for me in the "a-ha" moment, and too few resources explain the connections between concepts really well. khan academy being a strong exception.

How long have you been teaching?

Helena Curtis wrote a wonderful college level intro textbook as of 1980 when I last used it, but the publisher (Worth) let it die after she retired (which also pretty much killed them as I recall).