The crime is irrelevant. The discussion is whether you are guilty or not as an individual. If you willing commit a crime (regardless of how you feel about the law) then you are rightfully punished.
The problem is when you're innocent and still get punished anyway.
Well, if you stole a pack of gum and are executed for it, that's still a problem, even though you're technically guilty.
And again, in the real world, there are maybe hundreds of people suffering public outrage even though they are innocent, and there are tens of thousands of people who are serving extremely harsh sentences for minor crimes. The first is regrettable, the second is a major societal issue.
If you're guilty then you can disagree with the sentencing but it doesn't change the fact that you did the crime. Being considered guilty (by the courts or public) when you're actually innocent is far worse.
The US justice system is built on this foundation of letting the guilty go if it means avoiding a single innocent from being wrongfully convicted. Now you might say that social outrage isn't a big deal but considering the permanent nature of the internet and pervasiveness of social media, it's the same branding as a ex-con, if not worse since govt records at least have some controls on who can see them.
I agree that criminal sentencing and prison reform is needed, but that's a different discussion compared to how we treat the innocent.
The problem is when you're innocent and still get punished anyway.