No, not kidding.
There's a legitimate government interest in identifying people entering and leaving a country. This isn't Facebook, or even cameras on street corners -- this is a government responsible for enforcing legitimate immigration policies at a legitimate location (the border) for a wide variety of reasons (safety, economic, etc.), which absolutely requires knowing who is who.
I don't know any serious thinkers who claim otherwise.
And I don't see a particularly big difference between getting my photo taken for official ID's every few years (passport, driver's license, visas, etc.) and having it taken when I need to prove my identity with one of those.
The government already has photos of me. They already know my flight. How could it possibly affect my privacy that they also have a photo of me when I get on the plane?
I'm just not seeing it.
(Unless you're opposed to the whole concept of passports and photo ID's in general, but that would be a pretty radical position.)