The reason why many liberals push for gun control is very simple: it has the smallest human toll. To make criminal penalties stronger would have the effect of putting people for long periods of time in dehumanizing places such as prison. Such a result would be undesirable, because nothing crushes the human spirit more than confinement, and people need to keep their hopes up to be rehabilitated. I steadfastly believe that taking guns out of the hands of criminals would be much more beneficial than simply allowing them to commit the crime and then brutalize them.
You're very unrealistic. People don't commit crimes because they have guns. People seek out guns because they intend to commit crimes, and even if you are successful in denying them guns, which is almost impossible, they will find another way.
This type of thinking is a perfect example of the unrealistic view many liberals have of human behavior, and why liberalism has been so destructive to our society.
As far as "crushing the spirits" of brutal criminals, that's exactly what we should be doing. When a person reaches the point of being willing to kill a father in front of his child, or something like that, I don't believe that person can be rehabilitated, and I don't think we should waste more innocent lives trying. Rehabilitiation is for kids who get caught stealing hubcaps or smashing mailboxes, not for brutal killers.