This is not in any way a rant at any one particular games company - it's in reality an industry wide issue....
The problem is not black and white versus colour - but rather books poorly designed to be read in black and white (if they even were in the first place, most being grayscale), vs. colour.
Too many modern game books are simply grayscale pastiches of colour, rather than actually fully thought-out and designed B&W books from the get-go.
You must have seen the symptoms, over-dark computer generated maps and text that is visually far too dense, as well as having heavily shaded moiré'd (dotted) page backgrounds. Those are a few of the signs of sloppy design and lack of consideration of a book's final use.
Just because it is easy to do fully shaded and "glossy" grayscale, doesn't mean it's actually the best choice. A well laid out and purposefully designed B&W book is in many ways a contrast and a joy to read.
Shame virtually no one produces them nowadays.