The "suck" might please puritanical values. However, it doesn't encourage inmates to get on a better path. It just churns out bitter unemployable people with high rates of recidivism.
We have no way to check if they were actually an inmate or just a sock puppet for their political position. Even then, they never experienced the alternative, so they don't have any more information than we do. A classic "alternative history" problem.
We haven't experienced an alternate-history version of America without slavery, so does that mean we don't have any information on whether it was bad or not?
"Make prison suck" is just one possible means to an end (the ends being to deter crime and recidivism, and keep dangerous people off the streets), not an end in itself. For some offenders, the sucky experience is enough to set them straight. For others, their whole lives already sucked at least as bad as prison, so prison is just more of the same.
