Look at it this way:
The first major lesson WOTC learned examining TSR history was that you can't copyright rules. So they make the OGL, become game industry heroes.
At this point, they seem to have concluded that they can't just not copyright the rules, but making money off of them is not sustainable. So, they are looking to make money off of stories, and physical objects (coffee table quality core books, luscious but affordable starter set, DM screen, minis, etc). The rules, as such, are being given out for free. A penniless group of middle schoolers has full access to the rules, and most of the expansion material so far; this makes it easier to play without the qualms of piracy, and builds brand identity (the real money maker). Selling crunch is not their business anymore, it's selling fluff, because they can trademark fluff.