I'm not even sure they are participating in the same competition that many of us think they are.
Well, I tend agree with that. Just like with the complaints on "marketing failures" I remember from before the release.
They could win, if they just offered more info, but made it clear that DMs were free to pick and choose from them.
How does this improve the readability of the text?
If I gave you a large set of information, and then tell you: Maybe 50 % of the information is wrong or at least incomplete, would this help you?
That's what you risk getting if you don't distinguish well enough between player info and DM info, and if you keep a lot of stuff in that a DM is free to ignore.
You could try it this way:
DM book is condensed with a plethora of information, always reminding you that you can change what you want or ignore stuff.
Then you have the player book that can be used as a reference book.
But how much of the stuff that is not in the Player Book might become "core" of your game - and should be made public to the players?
How much of the stuff that is put into the Player Book might be stuff you'd prefer to trim from the DM book?
Alternatively, you could just have one book designed for DMs, with lots of info you can mix and match. But then you put the newbie DM in the position of selecting all those parts that he wants and then presenting the information to the players that are "true" (or at least supposedly true) for his group.
Alternative, you can just put some core information in the book, those that detail the setting in broad terms but narrow enough to have starting points and plot hooks. A newbie DM is still forced to make up stuff - but the bare bones to get a game starting are there. The players have the regional information they might need in their book. The DM will need the player book, of course.