I am in no way condoning the use of Cocaine or other illegal drugs but if they were to legalise and Police Drugs we would havea smaller Prison population and a lot more empty Hospital beds.
Maybe we would, eventually. But I find the most likely scenario, at least short-term, to be that of many people deciding that since they are legal then they must also be "safe", thereby multiplying the number of users almost overnight.
That alone is a very good reason not to legalize them.