I agree and it does seem to be getting worse.
It evidence's crew's disregard for passenger comfort. Particularly with all the delays these days, by the time aircraft's at cruising altitude, we may have been strapped in our seats for 90 minutes or more.
So if there's no turbulence, turn it off! Don't make the pax - many of whom are uncomfortable breaking rules - sit and sweat it out in discomfort. I eventually just get up and go. That usually starts a stream of pax who have also been sitting in discomfort and all of whom now feel kind of silly for having waited so long.