So, if strangers break down your door unannounced, you won't shoot at them just because they might be cops? If that becomes the message, expect lots of home invasions by the bad guys as a result.
If the cops are invading the wrong house, then it's the cops who will have legal problems. And if I'm on the jury, the cops will have more to fear from the justice system than the residents of the house--unless the cops properly announced themselves ("knocking" isn't the only way to do that, of course.)
Hey, sometimes the bad guys yell "POLICE!" as they enter. This is happening already, and everybody on the bad end of the invasion reports great confusion. It's one direct consequence of raids, period. Never mind no-knocks. As for "Wild Bunch"-ing it out with a paramilitary assault force, chances are real good at gettin' got, and who knows what version of events a jury will hear?