I assumed, (wrongly) that people would understand that the violence is active in the game. If your just driving around and such you are less liable to run into the extreme violence but the sex and cussing is more passive and you have more of a chance to see and hear that. It's like folks are trying to be daft however, I will own not explaining myself better. The violence is also a no go.
You want the makers of GTA to put in a mode that removes the swearing, nudity and... violence... and it's the rest of us who are daft? lol. The series is named after a major felony offence. This is just the "Dark Souls needs an easy mode" debate in different clothes. Doom needs a mode where the guns are candy canes, and they shoot puppies and rainbows at lawn gnomes, so my five year old can play it.
Not every game wants to be, tries to be, or needs to be for everyone.
If your kids just want a believable world they can drive trucks around in, might I recommend The Crew, or the Forza Horizon series?