Wouldn't it increase rendering time of all images? Lets hope he'll add outfits so the feature wouldn't be just for nudity toggle. I mean it'd be a waste of rendering time if it was only for that.
Last time I looked he renders all of the female characters naked for all scenes and then renders the clothing separately. So the render time on the clothing is miniscule since it's just the clothing and literally nothing else. So you're talking maybe 30 minutes or something to render the girl naked in some pose and then like 10 seconds per outfit to render however many outfits she could be wearing in that particular scene in that pose. It does still require set up time, posing, coding, etc though. It's not just render time.
I found the code particularly annoying when I tried that in my mod. I didn't use layers. I rendered the full scene using different outfits. Personally I didn't consider it worth the trouble. I just did it because the dev did that in the original game so I thought I'd play around with it as well in my mod.
One change he said he did make in the rebuild was to prioritize clothing that has built in morphs for lewd scenes like undressing, sex scenes while still wearing clothing, etc. Clothing without premade morphs is a massive headache to manually manipulate when you're trying to do scenes like that since it's meant to form to the character wearing it. For a scene that takes maybe 30 minutes to put the character herself into a pose you want, if you want to have a scene where she slides her skirt down half way, just managing to get her skirt into that position while still looking like she's wearing it might take you several hours if you can do it at all, especially if her legs are bent at all. So using clothing with built in morphs should save him a huge amount of time for any kind of lewd scene that includes clothing being removed or manipulated.
, just finding it very surprising for her to be doing this so soon narrative wise. 
