OK let me put my two cents into this topic. Take if from someone that was somewhat involved in the porn business in the past (this is an off topic discussion, and I don't want to get into it now). Firstly, Masturbation is indeed good for men. It has been proven to reduce the chance of Prostate cancer. Next the idea that it causes poor sight or makes your palm get hairy, I mean do I even have to address this BS?
Now violent porn has to be classified into many different parameters. Indeed original porn was based on violent themes, and many original pornography movies from the early 1900's had the sadomasochist themes. There were much milder than the themes we see today, but nevertheless taboo for their time. The whole concept of porn is to satisfy the often hidden desires of many people, who do not want to participate, rather just view such topics. Violent porn can be divided into really hardcore stuff (snuff films which are illegal and should be so), bondage (very big in Eastern culture specially Japan for a VERY long time) Spanking and rape theme simulation. Now the later one is being very closely monitored and is often times very close to being turned illegal.
Now I am not into any of the above themes, I do however enjoy porn like my friend Khorus, and I believe as long as someone is enjoying ANYTHING in the comfort of their own house, WITHOUT breaking the law and harming anyone is NO ONE'S business.