If they're right about what the President will say, more power to them, and him.  Conditions in federal prison are good, but this cannot uniformly be said for the states.  Same with health care and vocational training.  

Prisoners are our fellow human beings.  In the great majority of cases, they earned their way to incarceration.  But almost all will return to civil society one day, and for their sake  --  and more importantly for ours  --  they should be given every reasonable chance to lead a safe and productive life.

The reason our liberal/libertarian friends have mostly (if implicitly) given up on "sentencing reform" is, I suspect, that they understand that the President knows this actually means "mass sentencing reduction for drug dealers," a program he is wisely not about to embrace (and that, over the last couple of years, has, at the federal level, sunk from moribund to deceased anyway).

UPDATE:  Prison reform, though welcome in my view, can still fail if its advocates forget the old saw, "When you get greedy, you get burned."  I see from the follow-up story that some advocates want quietly to tack on a sentence reduction proposal, one that would water down mandatory minimums for criminals with more extensive or serious records.  They apparently view this as a clever idea to give the decarceration movement some life.  What it actually amounts to is a poison pill.  But I don't do their legislative strategy for them.