Castration would work for repeat offenders, but for some reason it has not caught on, dunno why.
Apart from being inhumane, it doesn't work. There's some evidence that it makes sadists worse.
While it might make people feel like super-humanitarians to offer counseling, CBT, and other forms of behavior modification to these people
It isn't about how people feel, it's about preventing re-offending. There are simply too many repeat offenders, and the light sentences for rape that are given in some countries (Poland gives noticeably lighter sentences than the UK) do not help this.
As for behaviour modification in gaol, in a civilised society, the purpose of the justice system is threefold: deterrence, punishment and rehabilitation. Stiff penalties aren't a deterrent (the US has an incredibly high murder rate despite the death penalty) and long sentences are expensive and give little hope or motivation for rhe offender to rehabilitate.