Bullet storm, one of the most violent games released this year, had a gore toggle. I got rid of everything, even environmental gore. Heck, it even had a profanity filter. Tuning both of these options on turned it into a Teen Rate game mostly (but I think they had to add a profanity filter in that game due to the obsessive amount of 'body part" jokes). Nevertheless, it's an option, so why not? It's not hard to implement since they have to censor the gore for the German version anyway.
IMO, it's pretty awesome when you're sick of seeing people go to pieces. I hope more game start implementing this feature.