I like that the fence moves with it. It seems like more of a complete vision than the moving sidewalks we have today, which always look like they were just dropped into a hallway.
We also seem to be unable to perfectly match food and hand speed these days. I’m not sure if this is a “feature” somehow, but it bothers me a lot. They didn’t seem to have this issue with the floor and fence, as far as I could tell.
I believe it's to allow room for the handrail belt to wear down, which brings its speed closer to the stairs until it starts de-syncing in the opposite direction. If it started perfectly, you'd have to replace the belt more frequently to maintain the same level of tolerance.
That’s because the systems are designed to be dropped into a hallway. In modern moving walkways and escalators, the treads and handrail belt return on the underside.
The system used in Paris requires a giant bulb shape to turn around the fence, which is generally a lot harder and more expensive to accommodate.