I don't mind a toggle or whatever. For me personally, I would just like to have the game as realistic as possible in whatever is shown.
That doesn't mean everything has to be shown. Romance scenes that just fade to black are perfectly alright. However, if you show stuff, than show it properly, for example, if you decide that you want to show Traynor in the shower than do it without the underwear. If you don't want to show nudity in whatever form, rather keep the camera angle to only show her head, shoulders and back like abut a gazillion movies do.
Same goes for combat. If you say that your bullets are as small as grains of sand and just cause internal damage or whatever, than I am perfectly fine with no gore animation. But if the description says that incendiaries burn people, than show me that and don't just make then disintegrate into little red flakes (yes, I'm looking at you, ME1 ammo mods).
Same goes for characters, if I am dealing with some rough rogues from the Terminus than I'd expect them to curse, but I don't want everyone to curse all the time just for the heck of it (ME and BW in general has done this pretty well so far, no complaints here, I'd rather look at the Witcher series for negative examples in that area)
For me, the most important thing to get into the game is that in game/universe descriptions and reasoning fit together with what is actually shown on screen. As long as this principle is upheld, I'm happy. Of course, if the devs decide that they want an extra toggle to turn all of that off, that's their business but IMO, for an M-rated title, it's not necessary.