FWIW, a friend thought the calves and feet only scene in Wet Hot American Summer was the finest sex scene he had ever seen. It's a product of its time, but it proves your point.

If it's at home, I don't mind something that is proportional and does the work of furthering the plot and conveying emotions. Film is an art form, so if it makes sense and doesn't last long enough for me to turn to my partner and say "uh....did we switch movies?" then it's fine IMO. 50-75% of GOT nudity was not necessary, for example. And we all know what was and what wasn't.

On a plane, I always freak out, like I'm some pervert that chose that movie to show the whole plane some boobs. I didn't know! I swear!