The separation of powers - the cornerstone of constitutional democracy - requires that the legislature legislates, not judges, and that judges decide law (and make relevant decisions of fact if sitting without jury - if they are sitting with jury the judge defines law and the jury decides fact) not legislators.

A different problem with both the UK and US systems at this period of history is that the legislature is not properly independent of the administration, but htat is another story.

What you are talking about, DT, is a situation in which the government (administration) has proposed and legislature passed laws creating powers for the punishments of which you approve to be imposed on thos found guilty as a matter of law and fact.

It is not the same thing at all as a judge deciding to create a whole new range of powers for himself to impose penalties not set out in legislation.