Garrison:  To begin with, I truly hope you don't think Judges wade through the 'books' on sentencing guidelines before issuing their sentence upon some defendant.  They don't!  What they do is to read the presentence report which contains everything they need.
Secondly, not all grand juries are secret.  As a practicing attorney, I can't remember the last time a client of mine was a subject of a proceeding where I was not advised of it ahead of time by the prosecuting attorney.
Finally, as you seem to think we should not keep 'throwing away the key':  Are you aware of the simple fact that for the last decade or so the majority of Americans believe sentencing has been to lenient and that we 'should' 'throw away the key,' (Check the numbers in Polling Report is you are not aware).  The reality is that by the time a person is sentenced to prison he has been involved with the criminal justice a number of times.  There are likely exceptions but there would be few and far apart.