Anonymous
You are, apparently, employing a form of moral reasoning called “utilitarianism.” Stripped down to its essentials, utilitarianism is a moral principle that holds that the morally right course of action in any situation is the one that produces the greatest balance of benefits over harms for everyone affected. So long as a course of action produces maximum benefits for everyone, utilitarianism fails to take into account considerations of justice, and does not care whether the benefits are produced by lies, manipulation, or coercion.
http://www.scu.edu/ethics/privacy/loss-of-online-privacy-whats-the-harm/
By tracking your online searches and communications, companies do note, do make assumptions about, and sometimes do disclose more than just the preferences and interests that you openly express. If you search online for information about sexually transmitted diseases or laws that protect whistleblowers, for information about domestic violence or the Dalai Lama, for Occupy protests or for sites that allow you to download songs without paying for them, a variety of entities will know—and draw conclusions about you based on those searches. You may then find that ads appearing on pages that you visit will reflect those subjects that you searched for, or even subjects that you discussed in emails that you may have considered private.
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Privacy is about much broader values than just “hiding things.” […] Ultimately the fullest retort to the “nothing to hide” impulse is a richer philosophical defense of privacy that articulates its importance to human life—the human need for a refuge from the eye of the community, and from the self-monitoring that living with others entails; the need for space in which to play and to try out new ideas, identities, and behaviors, without lasting consequences; and the importance of maintaining the balance of power between individuals and the state.