if I choose to go barefoot in a restroom, how is that any concern of yours or anyone else's but mine? I don't find it gross and it's my body, so I think that is irrelevant. What is relevant is threatening me with arrest for failing to comply with a made-up regulation. Makes sense, right?
BTW, I wear shoes from taxi to takeoff, and final approach through landing, as these are the times most likely to require an evacuation of the plane.