I used to work with the urban poor and many of the men had been locked up at one point or another. It is hard to move on and live a normal life after committing a felony, particularly a violent one. You can’t get many jobs, and depending on what you did, many people may not want to associate with you anymore. It can be hard to find a place to live too. This can be particularly cruel for people who have non-violent offenses and who are not threats to public safety or security, or for young guys who committed crimes as dumb, spontaneous teenagers. They are labeled as a felon for the rest of their lives. The successful ones usually require a lot of help. They need structure - a good place to stay, a place to work and make money, and good influences in their friends and family. Too often they don't have any of that, so the recidivism rate is high.
However some crimes are just completely inexcusable and people have a right to demand that society keep violent people away from their families, schools, etc. In these cases, it makes sense to prioritize society and the public above the offender. However I suspect the truly violent/sadistic/dangerous are probably not overly concerned with looking bad or being judged. They probably have a completely different way of viewing the world, and the regulations and stigma may just be an annoyance more than anything else.