Knowing and KNOWING seem to be two different things. WotC seems to me to be made up of people who play games for a living, not a quick pastime. It's hard to DM a homebrew AD&D game once you get into Real Life (TM). It's near impossible with 3E.
There is a philosophy out there that says that 3E is all about "player entitlement." I used to laugh at this, but it's becoming truer and truer to me as time goes on and I see more of the design philosophy behind the books. It also fosters metagame thinking, just in that no book is off-limits and the game plays most smoothly when players know all the rules (all 8,000 pages). I think the DM should be the boss (the boss of FUN), and things like "when the player points at something in the book and asks if he can buy it, the answer should be yes," really make me stop and wonder how and why the game has changed so much. Players, looking in the books? My GOD MAN! What's next?
Edit: Italicized part added, since I don't know anyone from WotC, and of course there are a lot of freelancers who contribute to the mountains of material.