Murder is always wrong, the government saying it's ok doesn't make it right. As someone else said, it's a step in the right direction.
The fact is that children can't be held completely responsible for their actions, and the law rightfully reflects this. Sure, some 17 year olds probably know damn well what they're doing, but they have to draw the line somewhere.
Now if they'd only get it through their skull that rehabilitation as opposed to straight prison time works much better...