One elephant in the room is that noise (film grain) compresses very badly and so movies that would otherwise be transparently presentable with a couple gigabyte

One elephant in the room is that noise (film grain) compresses very badly and so movies that would otherwise be transparently presentable with a couple gigabytes have visible compression artefacts in their BD-50 releases. And that almost all presentation is digital these days. And that in the days of digital everything and VFX, the grain is artificial anyway. AV1 mandates support for film grain synthesis. Maybe, one day, this will become a standard part of film production.