In the 5e books, at least, the problem is not just formatting.

The structural organization of the books is an abysmal mess. Rules that must be understood together in order to resolve common situations are often spread apart and buried in subsections of several different chapters, when they could just as easily be grouped in one place, or (at the very least) have direct references to each other. Also, ambiguous prose is often used to describe mechanics that would be better represented with keywords.

They're aesthetically nice, but as rule books, they needlessly burden the DM (and to a lesser extent the players), which takes time and attention away from actually playing the game.