There are two things I feel about this, first is prisons as they are in many countries are really bad for the employees, lots of suicide etc. As a prisoner being put away for years with minimal contact with the outside world is a really heavy punishment even if you live a life without constant fear.
A society that mistreat people is not something to strive for, and making prisons as bad as they can get will affect society as a whole. Paying prisonguards a little extra to take the risk of suicide seems really rotten to me.
Edit: this extends to warcriminals.
And if they are still dangerous, then, yes, you keep them locked up. But even then what's the point of making them suffer beyond the restrictions that are necessary to ensure the safety of the rest of society?
This means removing your freedom to move and not necessarily turtoring you.