In Boxing, the only way to win a fight, THE ONLY WAY, is to hit your opponent repeatedly. Boxers are commonly hit 100 to 500 times in the head during the course of a bout. The objective is to knock your opponent out. Boxing, admittedly much much larger than mixed martial arts, has had over a reported 500 deaths in the last 100 years. John McCain, was at an event who a boxer was killed.
Corruption is also an obvious factor that rules boxing.
The actions of Mike Tyson and others have also damaged the sport in obvious ways. This takes us to all of the content that is already allowed on cable. You can watch pornography on the Spice Channel. Pick any dramatic movie or T.V. show. There are numerous depictions of murders, rape, sex, etc.