Culture industries are dominated by a few big corporations that prefer to keep flogging old stories instead of taking a risk on something new. Creative workers can still produce fresh ideas, but they’re snuffed out before they get a chance to breathe.
There are two noteworthy points in history featuring boobs in cinema.
The 1980s in the US is the era of the slasher flick, and the film student age, so Lucas, Speilberg, Coppola, etc.) when arty films started getting a (tiny bit more of) a budget. It’s also before the internet, so one is not able to just look for boobs on the internet.
As Sarah Marshall notes (discussing the history of porn) these R-rated movies are the only place where a fellow might see boobs other than his partner’s. The early internet (and its predecessor, usenet) provided a lot more boobs, and so boob content fell off from mainstream cinema in the late 90s and early aughts. DVD is also a factor, which not only didn’t require MPAA approval, but often advertised The Unrated Version and we got to see a lot more European movies which were a lot more relaxed about boobs.
Also, we get plenty of boobs in TV series on Netflix and whatever HBO is called now.
But then there’s what happened to Spanish cinema after the death of General Franco
He died, and his extreme censorship was quickly lifted. Spanish Cinema went through The Stripping Years in which films featured at least one gratuitous sex scene with boobs and pubes (we weren’t all trimmed French or Brazilian yet) simply as a celebration of freedom of expression. So if the Republicans succeed in taking away everyone’s porn, there will not only be extra-risqué black market films, but the US mainstream cinema will likely go through a boobalicious phase because now we can show this again!