Take a look at humane prisons that work in other countries. If treating people humanely meant that folks learned more criminal ways, Norway would have an awful time with this. The opposite is true, however. For the most part, folks are committed to trying to make the prisoners a good neighbor upon being releases - from day 1 of being released.

What you describe - some of the prisons of the "old days" also produced ex-offenders that were seriously mentally ill. That is very easily the effect of having solitary of that sort for so many years. Even if you do wind up being able to mentally withstand the place, you get released with no knowledge of what has happened - which happens now, actually.