I have definitely noted an increase in this predicted turbulence/stay seated phenomenon. On a handful of flights it was so pathetic passengers in first were using the forward loo.

And I'm now west coast/Pac NW based mostly flying.

For perspective following the merger (going from a NWA Platinum) to Delta I was driven nuts by the tendency of Delta F/A's to stay seated until well into cruise. I asked around back then and was told there were certain stations, mostly the southern, where the crews just sat until the seat belt sign went off (MCO/TPA are two bases that were mentioned). Whereas with NW they almost always were up after the 10k chime.