And the mentioned books, at least some of them, serve different purposes: they aim to inspire, to motivate, and to offer historical context and intuition. The last is especially important, as they show people how abstract concepts emerged from historically concrete endeavors.
When it comes to learning math, you can't take an elite's view. Not everyone is born Bourbaki dudes or Galois or people like them. Ordinary people like me don't just fall in love with maths. I was certainly not interested in number theory as I thought it was too fundamental for me to spend serious time on. And I'm still not. I was certainly puzzled on why my professors introduced the concept of functional in linear algebra or quotient groups in algebra or lattice equations in program analysis or category theory in model checking or probability space in probability. After all, all I wanted was to learn how to model the world to be a better programmer. And I was not able to grasp the abstractions without serious effort. I needed historical context and motivations to plow through those topics and to enjoy math.
Yes, the elites will love and excel at math for no particular reason. Yet it is the middle majority like me who will greatly benefit from the mentioned books and biographies and what not.