That's not the argument I'm making. Yes, there will be a lot of really dumb things on cars if you have a wide open livery editor, that's the nature of the beast. I'm sure the vast majority will be creative and interesting. What I can see though, is Kaz having nightmares about websites devoted to pornographic GT6 liveries and I don't think that would sit well with him and he just doesn't want to deal with it at all. Along with that, you'd have no choice but to have a reporting function that will have to be staffed by real people at some point and this costs money and drives people away from the game, something else I think he's loath to do.
Has everything to do with Kaz and not much else.