"What's the big deal? If you don't have anything to hide why should you object?"
That answer to me is just wrong on so many levels. Superficially, though, it has merits.
The next time somebody tells you that, ask them to empty their pockets, their purpose, and their wallet, strip in front of you, and give you access to their email and digital records. When they object, throw the question back at them.
There are very few people that would actually submit themselves to such treatment willingly. There are far more people that think it is okay to do that to SOMEBODY ELSE. The mental self-delusion is that it would never really be applied to them, so they are ok with it.