Someone has not read many mathematical books on a Kindle (or even PDFs on an iPad), let alone seen the intricate typesetting of TAoCP. For an epub the configurable font size alone wreaks havoc with mathematical typesetting, and converting them to pixelated versions fails as screen resolutions go to higher and higher DPI.

It's a monster of a problem, which still isn't solved. As good as TeX/LaTeX is at handling paper sizes, the screen sizes / DPIs / pagination / font sizes of eReaders is a far more difficult platform to target.