The D&D law has always been used to arrest people they just want to arrest.
Drunkeness is not a legal problem, it is a social and health problem, and should be treated that way.
If drunks act in ways which threaten others or disturb the peace (whatever that means) then there are plenty of laws to arrest people for in those situations.
If you really want to get crime rates down, legalise drugs, all making them illegal does is increase the price and ensure anyone who has a drug problem is treated like a criminal rather than someone with an addiction problem. It has never seriously had an impact on the ability to source drugs, although it does push the price up - good for dealers. Also the drugs which are made illegal is selective, alcohol would be the drug which causes the largest number of problems but is legal, yet marijuana is illegal and causes way less problems.
DS