Why waste valuable resources on someone who contributes nothing to civilization for the sake of some arbitrary form of psychological punishment? All we're really doing is draining our own pockets to keep 'em alive. Me, I'd rather bury them and move onto the next problem than worry about containment, security, food, logistics, etc.
How in any way is it arbitrary?
And I would say expending government resources to imprison those truly deserving to be there is not a waste... it's exactly one of those things government is there for.
American justice and prison systems are an absolute joke - we have more prisoners than any other country in the world.
Prison system is a problem, but this is not because of the types of violent/psycho individuals we have been discussing. This is largely due to the "War on Drugs" and the criminalization of what would probably be more appropriately handled in many cases as a health and/or psychological problem.