Programs to reduce recidivism cost money. But even if their succes is somewhat less than 100% they return many dollars for each dollar spent in prevention of future enforcement/imprisonment events. And for starters, a whole buncha resources for such programs could be freed up if we would just stop legislating personal behavior where society has no business meddling, like sex and drug activity in which no minors or unwilling participants are involved and no property is damaged.

And as much as I think some of the criminals prominently mentioned here are not part of civilized society, I still think executing criminals should not be done. It is, as has been pointed out here several times, much more expensive than a life sentence; it lowers society to the level of the killers; and it deprives us of the chance to have them possibly live to regret their actions and show remorse.