An open information policy, regardless of it's supposed higher morality, reduces a social network's ability to compete, because a) it gives competitors an advantage in acquiring your users and retaining them, and b) the vast majority of users do not care about this. We have the current equilibrium in the social networking market because of many forces, including ease-of-use, social feature set, up-front monetary cost, and social group inertia, but information policy has empirically proven not to be one of these factors. It has, however, been an important factor in shaping the self-publishing/blog market. There are different solutions suited to different markets.
And you cannot explain people's indifference to this issue by proclaiming (arrogantly) that they have a "lack of knowledge". People have other more pressing concerns in their lives. Making the rent this month. Dealing with a child who is not performing well in school. Internalizing stress from their job because they are not trained enough to get a better one. Even if the average person did know about information accessibility, privacy, and sale to 3rd parties, why would this issue rise to a level comparable the issues listed above? The fact that they can smile for half an hour when they get home from work by reading/looking at a personalized listing of information they find valuable, and do this for free, is all they need to know about the web. This is not for better or for worse. It's reality in all its complexity.
If or when this free-but-centralized/closed system fails them, by directly affecting their pocketbook or by itself has becoming insolvent, is when they'll take notice. And if this does ever happen, it is probably decades away.
Lastly, if you aim your service at just "the people that care about information access", don't overestimate your market size. You going after a much smaller pool. With social/communication services, we're not just talking about a pool of individuals, we're talking about a pool of friend/colleague/interest groups. In this case, the specific pool is basically all friend/colleague/interest groups which are comprised entirely of libertarian-minded nerds that actually want a communication service beyond email/mailing lists, github, and blogs/comment threads.
Ferchrissake, this comment thread on Hacker News only generated 19 comments; what do we need a whole social networking service for?!