First of all, extreme deterence engenders a climate of terror in the populace. A peaceful civilised society should try as much as possible to eradicate these aspects of human psychology, rather than actually fostering them. So, we must strike a balance between effective deterence on one side, and humanitarian ideals on the other. Our society has yet to find this balance. Our current criminal justice system seems motivated mainly be the idea of deterence, and this deterence-based system currently seems to be spectacularly failing.
Isolation seems sensible, but it isn' t really a solution.
Finally, isolating criminals en masse seems to do nothing but encourage their criminality. A young person is imprisoned for some minor felony. After surviving 5 years confinement with bitter, violent, sociopathic individuals, and also spending those 5 years learning their skills and secrets, he emerges with his criminal abilities, and his criminal tendencies, multiplied ten-fold. This is hardly an effective long-term preventative measure. Remuneration seems like a good idea, but in practice, is somewhat laughable.