I believe, Loos wasn’t talking about the ornament on a banal level of a façade plasticity. He was talking about the bad taste in architecture, and it’s catastrophic consequences for the culture and the city. If you think about it, the crimes against the good taste in any society get heavier with the rise of the social stance of the perpetrator. So, when one reaches a certain level of influence, the bad taste can be a crime much uglier and less forgivable than a murder.
Loos was telling to us architects, that we are inherently in a position to commit a gruesome crime, weather we are aware of this or not. Moreover, our power to do a LOT of long term damage to everyone is not in the least proportionate to our social stance, and maybe not even to the good that we bring when we do something perfectly.
Luckily, he had also shown us a way to win (one of the ways at least)