This is a cool idea but it is a bit sad that it is necessary. Sad because it is wasteful. Books are written in a digital format. So we are using natural resources to make them, turning them into digital (which they already were, and probably in a better format then PDF like LaTeX, specially for technical books), and then destroying the physical copies after they consumed resources.

Of course it's necessary because not all publishers release digital versions or they release it with a ton of DRM, etc..

Still, it's a bit sad.