Love Draculino and have really nothing but great things to say about him and agree that the guard is a great skill set and dangerous to deal with when the practitioner knows what they are doing. However, Hanzou that is all compliant playing around. There were a couple of times in that video when Draculino could have easily been bitten. That was a compliant fun video no different than compliant videos you poke fun at. It would be really interesting though to have a grappling tournament where biting was allowed and encourage. Would love to see the results. lol (not really though as that was a joke as it would have a serious gruesome bloody mess)
I know of know BJJ practitioner that routine trains grappling to avoid being bitten around the neck and in other vulnerable parts. The art has a glaring weakness in this area. If they did they would look very closely at a few details to work to negate it. Now, I do not advocate biting. The reason for that though is that I really do not want someone's blood in my mouth. (still if I had to) I advocate positional dominance that allows you to break, choke, strike someone. Yet, to dismiss it is foolish.
Your comment about wearing a shirt or pants are not going to provide you any protection from someone biting you. Jeans might give you a modicum of protection but the human bite is pretty strong. Not to mention your neck, face, ears, biceps, etc., etc. typically do not have a covering that will stop a human bite unless it is very cold and you are wearing a coat. This is a weakness in your thought pattern. You routinely dismiss things that are at this point outside your comfort and knowledge zone. You need to get out and experience more training just to broaden your perspective!