It's real simple: this is apparently what "people" want, based on their behavior.
Alternatives (paid, and cheap) have attempted to make your "social media" something where you're the customer, not the product (see http://app.net/ - "people" have mostly rejected it, whether on philosophical grounds (I'm not paying for this!), or for critical mass problems (But everyone I want to talk to used Facebook!). Primarily, it just seems that they want it free and don't value being a customer - they're fine being the product.
THAT, in turn, leads to this: Facebook will keep testing where the black, thick boundary line is that causes too much pain until it they overstep and do too much damage, then they'll back up just a little. And wait. And then test it again, maybe in a slightly different way. They're only slightly less insidious than the government here-the government just keeps attempting to ram the same thing through/down your throat until total rage fatigue sets in, and not enough people still want to fight it.