I think "violence" is in the kokoro or mind/heart/spirit/intent of the person not the technique.
As a tornado is not violent, but powerful and possibly destructive in our eyes, budo waza is not violent unless accompanied by violent intent, hatred, malevolent energy from the person who performs the technique.
I took part in almost three years of combat in Viet Nam and only felt violence in myself on three occassions and I'll never forget that feeling. I really believe that we can be compassionate and still do what is necessary to carry out self-defense even in wartime.
I believe the nature of budo is compassionate even though some times we must use strong measures to achieve peace.