Oh thought males would probably be more comfortable doing nudity than female actors because female actors sometimes complain about how they were sexually exploited in movies, such as Sharon Stone or Scarlett Johansson, but I never heard a male actor complain about it and therefore thought they would be more comfortable doing than women more do possibly.
Well, speaking about the past or now?
I don't know if we know about the past, because they weren't being asked to do it. I seen to recall Patrick Swayze or Stallone talking about feeling really exposed just showing their butts on camera for Tango and Cash (but that's a stretched memory).
IIRC, young Ewan McGregor tried to show off his dong as much as he could.
There's a lot of power dynamics in play, so IDK. I suspect the discomfort was probably more from either, the directors, the producers, or their perception that the (male) audience would feel uncomfortable. Some of it is a self-perpetuating thing. No one does it, so it feels weird to do it, which leads to no one doing it.
The quote from von Trier about Defoe's dong for Anti-Christ is amusing.
But as for the NC-17 rating, I thought it didn't matter anymore near as much since people hardly go to theaters anymore and just watch movies at home now anyway and therefore would not care about the rating?
Last I checked the box office still exists, and the recent shift to streaming had a dramatic jump literally only a couple years ago, so who knows how that's going to impact what gets made going forward (it can take some time before people realize the rules have changed in terms of what is the most profitable and then also time to actually make movies according to those changed rules).
I think one thing that's been touched around a bit is what we mean by modern entertainment, since it's been mostly implied the big pole blockbusters. And those probably still need to appeal to as many people as possible (which means alienating as few as possible).