Yes that would be wrong. Sentences should be imposed on a balance of a number of factors, including punishment/deterrent, likelihood of rehabilitation, justice for victims and the safety of the public etc.
I am fairly sure from all the real crime docos I have watched, there have been psychopaths who have faked their rehabilitation and murdered again as soon as released. A lot of times the surviving victims are in a living hell going to probation hearings for early release, not to mention release after a short sentence. If it was me, I would throw away the key - no hand wringing from me. Sentences are generally vey light here in Australia compared to the USA.
One good new welcomed sentencing law in NSW (not sure what the status is in VIC), is the so called, "No body, no parole". I think that is the only reason the recent accused murderer of the gay couple disclosed where the bodies were.