I think the uber-real motion is due to a separate TV setting called video interpolation. At least, that's what Tom Cruise told me.
It’s probably motion compensation that tends to be enabled by default on most TVs that’s causing a headache. It’s been around since 1080p days, not strictly 4K related.
I can see what I'm talking about in this YT video. I guess I assumed it came from a 4K source.