Stormonu
NeoGrognard
This has always confused me, I don't really think there should be "player books" and "DM books" for game systems. I prefer game systems with a little more transparency about how the game is run (i.e. Burning Wheel). I don't like having sections of the rules "for the DM only" because it seems like the game designers don't trust the players.
I like one rulebook core books as well, but for D&D, its more than trust issues that causes book bloat. If we want a sizeable collection of spells, magic items and monsters like the books of yore, we're either facing big books and/or many books. That's why I'd really like to see a begginer's box (an all-in-one game) and then the standard book collection (PHB, DMG, MM for cluttering the game as much as anyone wants).
For me, personally, I don't think we need to be cluttering the player's section with long lists of magic items (they're generally not a starting resource) and monsters - it's not so much a case of hiding it from players but leaving room for other content or slimming down the size of the book. Spells are somewhat debatable - you need the 1st level spells for sure, but everything beyond that is up for negotiation.