It seems misguided to dismiss the technology itself, rather than scrutinizing specific uses. It reminds me of David Deutsch's book The Beginning of Infinity, which has an extended anecdote about a scientist who deeply objected to the development of color TVs because "people didn't need them" and he could only think of examples where bad actors would use them. Fast forward several decades, and color TVs are used for all sorts of important outcomes, like life-saving medical imaging technology, or sharing video of an important life moment with someone who is too sick to travel.
You could imagine similar things for face recognition. An Alzheimer's patient who has a large digital photo library of family members and events, and would like some information retrieval tool to help search for a specific memory, family member, etc. Or someone who takes stock photographs and wants to photoshop bystanders out of the photos so that nobody's image rights are infringed when submitting the stock photo for publication-- might want face detection to aid in the person-removal task.
I agree completely with scrutinizing motives and refusing to work on tech when the goal is unethical. But I don't agree this allows us to point at a generic, amoral technology in and of itself and say it's conceptually unethical for existing. Maybe there would be some extreme or contrived cases when I would agree to that, but even this face recognition stuff is very far from it.