Its not just the maximum sentence that should be increased but the minimum. There is too much power given to judges to reduce sentences for mitigating circumstances and guilty pleas.
Currently a judge can reduce a sentence if someone pleads guilty and saves the victim or their families the ordeal of a trial. The correct way would be to INCREASE the sentence of they pleaded not guilty, but were found guilty, because they put the victim or family through the trial.
There should also be a drop dead minimum sentence for crimes and the judge should only have the power to increase the sentence depending on the severity. Eg, murder should be 25 years but time added if the victim suffered through, say, being tortured or a brutal death such as being burned alive (as opposed to instant death caused by a blow to the head).