That's something people forget about our justice system, it works on the principle that *most* people can change their lives around and only certain individuals need to be kept away for longer.
Also, don't forget that there's a big difference from being sentanced to 9 and a half years compared to the life sentance with an 8 year tarriff to serve. The former case, he's a free man at the end of his sentance, in the latter, they can be sent back to prison at any time (as the news stories prove).