For years, Facebook users have been clamoring for better privacy controls and clarity, while Facebook engineers oscillate between improvements and major privacy snafus. Every now and then a new wave of exasperated users cry out "That's it, I'm leaving". Up to now, users really didn't have anywhere to go after quitting, so they effectively quit the social media scene, self-ostracized (MySpace is equivalent to being exiled, perhaps worse). Now that they have somewhere else to go (Google+), Facebook is ramping up its privacy controls and seems to be taking privacy more seriously. Let the privacy competition begin!
Despite Google's promise to "do no evil", all corporations are really amoral. They're neither evil nor good, nor do they take most actions within a broader moral framework. Corporations are either profitable or not, and the most important question for consumers is not "is my provider evil", but "is privacy profitable". If privacy is profitable, companies will differentiate on privacy and consumers will win. That only works though, if there's sufficient competition to make it necessary for an ad-supported service to pay attention to their users.
When all you can do is walk away
In the social media world, users are not the "buyers" of the service. They are, quite literally, the product that is sold to advertisers. Users only matter as a source of profit if they are rapidly growing or declining in numbers. The only leverage we have over the corporate-owned social media is our choice to walk away. Unfortunately, social media have become the new meeting grounds for social interaction, just like churches, schools, parks, coffee shops and malls. So "leaving" really implies cutting off all social contact with people who are not geographically local to you. That's not an easy step.
So it really matters whether there is robust competition in social media. Without it, we are a captive audience (quite literally) and will gladly exchange privacy for social contact. Google+ may be better or worse than Facebook. But that doesn't matter as much as the fact that they're big, funded and there. That's enough to provide a serious competitive threat in a market that has few entry barriers and low switching costs. It took me about fifteen minutes to transfer all my contacts from Linkedin and Facebook into Google+. My network was recreated at zero cost and with the added opportunity for some "cleanup" (perhaps I should have not friended that high school acquaintance...)
Joining Google+ might make Facebook treat you better
Even better for competition, Google+ actually emphasised better privacy as a competitive differentiator, forcing a comparison and response from Facebook. So even if you think Facebook is better than Google+, here's a consideration: Joining Google+ will actually make Facebook better for you. If you show you have somewhere to go, they will try harder to make you stay. If the primary differentiator is privacy, or you make your move in response to privacy changes, you can push the entire market in the right direction (you and a few other millions).
At last, privacy is improving not because we demanded better privacy but because we can put our clicks where our mouth is: shift our daily attention to another service and watch the market respond.