I highly doubt the acetaminophen in vicodin is to limit abuse. Some of the pills I've seen are 750/5mg. Even a moderate addiction of 100mg a could easily kill you at that rate (that's 15g of acetaminophen). Though if you had no choice, a simple cold water extraction will eliminate enough of the acetaminophen to make it safe.
While not quite as evil as all the deaths and stripping of civil liberties the "drug war" has caused, this is a pretty obviously wicked thing to do (while still ineffective).
I would submit to you that deliberate contamination of a drug for the sole purpose of inflicting harm in search of a greater good is an outrageous policy.
Adding risk (whether it's the risk of liver failure or prison time) to addiction behaviors doesn't do a damn thing, because addiction is a disease that fundamentally destroys our ability to make rational cost-benefit decisions when our drug or behavior of choice is concerned.