If privacy is really private, and not merely a promise from a benevolent entity they won't look at your details, not that they can't, then you will always find in your company those who need privacy because they are hiding from all of society that hate them. Even if we were to go 100,000 years into the future where morals are entirely different and alien to modern day ones, if privacy exists at all, you'll find it most popular among those whose behaviors are the most morally repugnant to the futuristic society.

Privacy is good even when you have nothing to hide, but it is imperative for those who do need to be hidden. The ethical issues I generally see people concerned with are ethical issues with privacy itself, not a specific implementation.