What other arguments have been given? Alcohol is the only major drug to have been re-legalized after being banned in America.
"Can we say that the social ill-effects are completely imaginary"
What social ill-effects can you cite in the case of cocaine-infused soda?
"The article seems to be suggesting this, but stops short of saying "let's start drinking cocaine again". Is the journalist ultimately unconvinced by his own arguments?"
It is politically incorrect to argue against the war on drugs, regardless of the damage it has caused to society (much greater than any damage the drugs themselves cause). We are trained from an early age to assume that drugs are bad, and to assume without question that drugs should be illegal (naturally, "medicine" is in a different category). It makes no difference whether or not the war on drugs has been productive, effective at solving any constructive goal, or in any way beneficial when everyone is fed DARE-style propaganda from age 5.
The reality is that in today's world, we should be more afraid of the DEA than of the drugs they "regulate," since their form of "regulation" involves assault rifles, grenades, and tanks (yes, really, surplus military vehicles including tanks and helicopters are routinely transferred to law enforcement agencies). The DEA, like the FBI, has amassed so much signals intelligence power that they are considered to be part of the US intelligence community. The DEA can and does recycle the proceeds from seized property into its own budget -- a practice that was authorized in the 1980s. The DEA can declare drugs to be illegal, without congressional action, for a year -- and prosecute people for possessing or distributing those drugs. The DEA can override congressional recommendations on drug regulation, as they infamously did with MDMA (ecstasy).
Meanwhile, with only two major exceptions, we are getting no tax revenue from recreational drug sales, there is no regulation on the purity or safety of recreational drugs, doctors have no idea what drugs their patients actually ingested, there is no age limit that drug merchants respect (high schoolers can buy cocaine just as easily as working adults), and criminals have access to a massive, steady, and enormous market. There is no time that would be "too soon" to end the war on drugs, develop useful regulations on recreational drugs, and restore our democracy.