While Pacifism admirable, and non-violent solutions should be strive for, I can respect a person who knows when violence must be used and in that moment hold nothing back in skill and dedication.
The idea of self defence and martial arts is that a proportional amount of force can be redirected towards an attacker. It is not a no-holds barred scrum. The entire idea of martial arts is to cultivate better ideals in one's self, not to be destructive.
I do not refer to "not holding back" as beating someone down, since if they are unable to fight back then the violence is no long necessary. If anything, defeating your opponent without throwing a single blow is the greatest representation of martial prowess. Merely that should your hand be forced, then let that hand fly true.
I was more considering the defense of others rather than self defense, though it's my fault for not referring to that.
I'm an advocate of the idea that if you do need to resort to violence then you should go full on, no holding back in order to cause fear.
Example: You're at a party, you're drinking, your friends are drinking, everyone is having a good time until someone starts making trouble and resists the efforts of you and your friends to resolve it peacefully. Basically this is a guy looking for a fight. Now, is it better to take him down with the absolute minimum amount of force possible, or to give him a beating him and his friends won't forget?
I believe that you should always try to head off confrontations
long before they happen, which leads to me believing that if you knock a guy out quick, the his mates are gonna come after you later, but if you beat him down, break his bones and smash his face open, then no one who witnesses it or the result will dare take you on.