See, that might be cultural background or whatnot, I don't know, but some people find those cartoons to be a nice touch, and they admire the clarity of exposition of The TeXbook.

I'm the proud owner of the entire 6 vol Computers and Typesetting series (of which the former title is vol A), and have worked through sizable portions of those. I also read mot of the 680 pages of Knuth's Digital Typography monograph. I also owned one LaTeX book at some point. I admire the depth of Knuth's knowledge (typographic and otherwise), the sheer diligence, his quest for quality, all of that. Those lion doodles though, the author's urge to land another witty remark, come up with another finely crafted reference, and how he's prone to hint at stuff instead of writing a proper documentation are not aspects of his work that I enjoy.