You said: True, these are very sad stories but to be honest I have little problem with this decision; technically (and that is the law) they were NOT adults; if they get a lifetime in prison it is fine with me, the hell they live in there is deserved.
The problem with this decision is that it strays from the constitution, and, once again, legislates rather than interprets the law. To be convicted of first degree murder one must be able to form the requisite intent. Age is not relevant to this, and certainly one cannot find any suggestion of age in the 8th amendment. This is a decision, once again, properly left in the hands of state legislatures, NOT the courts.