1. The hypothetical situation you mention-- a world without privacy, where everyone is already used to it-- doesn't provide any substantial defense of the present violation of our existing privacy. Similarly, one could posit a scenario where everyone has lived their whole lives under a totalitarian regime, and felt scared if it was taken away. Such a scenario would not provide an argument for totalitarianism. (One could conceive of such hypothetical situations for any arbitrary state of events: e.g. racist societies, societies that have genital mutilation rituals, etc.)
2. "Do we need privacy?" is a more generalized question, which, in the current state of much of the first world, presupposes "should our privacy be stripped away?", before "Do we need privacy?" can even be fully answered. I personally have no desire to test it out.
3. To further critique and rephrase your statement: the real issue is not "Do we need privacy?", but "should we have privacy?", or, "should we continue to lose privacy?", or, finally, "Do we want to continue to give up our privacy?"
2. "Do we need privacy?" is a more generalized question, which, in the current state of much of the first world, presupposes "should our privacy be stripped away?", before "Do we need privacy?" can even be fully answered. I personally have no desire to test it out.
3. To further critique and rephrase your statement: the real issue is not "Do we need privacy?", but "should we have privacy?", or, "should we continue to lose privacy?", or, finally, "Do we want to continue to give up our privacy?"