I think it correlates more strongly to the prevalence of pornography. Mainstream movie scenes look fake and contrived, because they are. As unrealistic as pornography is, that is actually a dick, and it is actually going in a vagina.
When your mainstream movie sex scene is going to be compared (unfavorably) to a scene of two people actually fucking, why bother even shooting it?
The human capacity for reason is greatly overrated. The overwhelming majority of conversation is regurgitated thought, which is exactly what LLMs are designed to do.