I agree that the degredation of morality is a major problem in society today. I would differ, however, that this is an argument in favor or prohibition. Indeed, I would argue the opposite: passing and enforcing laws without widespread support for them does far more to undermine society than would the lack of such laws.
Until recently, there wasn't much need for large numbers of law-enforcement personnel because such personnel would receive the support of nearly the entire citizenry. In a sense, nearly everyone was a part-time cop who might sometimes provide assistance at a second's notice (literally: cop sees crook running down the street and signals for anyone who can to stop him). Citizens saw the police as their friends and allies, and were thus generally more than happy to help out when the need arose.
Unfortunately, to an increasing extent, cops are becoming adversarial masters over the citizenry rather than being their allies and servants. There are very few people in this country who are 100.000% law-abiding. There are so many laws that nearly everyone is either guilty of, or has friends who are guilty of, things that they don't think should be crimes. In such an environment, police are no longer allies to be assisted, but rather enemies to be avoided.
Any law which is strongly opposed by even a third of the citizenry is a bad law. Efforts to enforce such a law will turn that third of the citizenry against the government. Unfortunately, many laws today get passed with complete contempt for any opposition. It should be little surprise, then, that the citizenry return that contempt.
87.4% of statistics are made up.