I like the three books. In fact, I prefer it to one-book systems. I like knowing that the players don't need/have to buy all of the information that I do to run the game in order to participate - and it also helps separate information - do they really need monster stats?
Even when distilling a system into a single book, you still end up with more material (and thus paper and ink, and thus money) in every book you turn out. This increases the barrier for entry into the hobby by what - 10 bucks? Something similar to that, if the PHB vs. D20 Modern example is any indicator.
What seems to have been glossed over here is that players don't need the whole system - they just need the *player's* part of the system. The rest is just a way to keep the company going.