on the ball-
I think you are making a serious mistake, factually and practically.
First of all, I believe you are incorrect. Chazal say terrible things about lots of aveiros, it’s their way of giving mussar. Look at what they say about anger, nivul peh, lashon hara, and lots of other things. There is a very simple reason why they weren’t ma’arich very much about murder – people already appreciate how bad it is, but obviously it’s worse (Let’s start by mentioning that it’s one of the 3 chamuros and it’s one of the 7 mitzvos).
Secondly, even if you are correct, at the end of the day you cannot and will not ever change the fact that people are more sensitive to murder than to chillul shabbos. You’ll say – so what, it’s the truth! But the point is, when you tell people something that goes against their deepest feelings they will not take you seriously. I’m not saying not to criticize, go ahead and tell people they’re doing the wrong thing (as long as they actually are and you follow the guidelines of the halachos of tochacha)! But be careful that people shouldn’t look at you like you’re crazy, or they’ll never listen. And if you tell people that chillul shabbos (l’teyavon, and b’tzinah too in most cases which I would assume was not what chazal were referring to) is worse then the Kletzky murder, that is exactly what nearly everyone will feel, even the frumest of the frum, whether you like it or not.