You got it reversed, this is the justification that has been put forward for the law to come into existence in France.
The basic idea is that non-verbal face-to-face communication is culturally expected as a very basic and fundamental part of our social interactions, however inconsequential they seem. An example: bump into someone on the bus, and you'll instantly look at their face to know if they're hurt or annoyed or sorry or vindictive without a word, and can proceed on with appropriate verbal communication. In other cultures maybe arm language suffices but in a European one it creates unease at best not to see the other's full face.
This is basically why even ill people don't wear masks around here (when it would really help not spreading diseases like flu) which is, I hear, basically a given in Asian cultures.
The French government decided to make a statement about it and declared that masking your face is illegal (barring a couple exceptions including medical reasons, safety, and cultural†† events) for cultural and security† reasons.
† Obviously terrorists vet in favor of RFC3514 and choose to wear masks in public and so everyone is now safer what you didn't think of the children did you?
†† Otherwise that would make for an interesting conundrum