The problem, folks, is that RPG rulebooks don't serve a single, focused purpose.
Concise, clear writing is great... for a reference book. It is great for someone who already knows what they are doing, and who already knows they want to buy the thing.
It is bad for learning, though - you all had really dry textbooks in school that were terrible to read, didn't you? It is also bad as a marketing-object - if the person isn't sure they want to buy that book, a wall of clear, concise, dense text will not get them the idea of what the game book is about without them having to read most of the book before they buy it. For these purposes, you need art, text that's evocative, and such.
So, as long as your RPG book has to do triple duty as a reference work, a teaching work, and a marketing artifact, you're going to have to accept compromises.