This is one of the few issues that thinkers on the left and right can agree about. Depending on which way your politics lean, you can read comments from Justice Stevens and Judge Alex Kozinski, or Justice Scalia and Judge Richard Posner (to pick just a few prominent jurists popular stereotyped as being liberal or conservative). All have expressed opinions about the shortcomings of criminal justice policy and sentencing in particular.
The root of the problem is that those who enforce and administer the penal system have a huge economic interest in maintaining or expanding it. While a good many people point to this as an example of why government is bad (monopoly on the use of force etc.), the sad fact is that very often people vote for this sort of thing in referendums. California's 'Three Strikes' law is a famous example. It's a terrible policy IMHO, but it wasn't foisted on the state by the government. 'We the people' put that one in place, along with quite a few others since.