Unless they enter the wrong home, or there are people in the home that have nothing to do with the "violet history" of the suspect.You have this wrong. What I have done is not expressed to you the possibility that the persons inside the home may not actually be guilty. Here is why, when police go to homes in this manner they almost always know the violent history of these criminals.
You are making a judgment call here. I am not opposed to making a judgment call, but "no knock" warrants need to be rare and provided only with significant oversight.The few times that they are wrong is insignificant to the danger posed by exposing their intents far to early.
Police should also uses every means at their disposal to gain intelligence about who is in the house and look for opportunities to arrest without a "no knock" warrant - if time permits. It's simply a pro-life position.