Prohibition of anything where there is a demand for it does not work, and it creates a criminal class where none existed previously. It also (as your linked article states) creates and feeds a criminal network, with the attendant violence (beheading in Mexico) and untaxed revenue that can also be used against the state which funds it (drug money going to fund terrorist organizations).
I will compare two popular activities here. Recreational drug use and illegal immigration. They are actually quite comparable on many levels, even though I draw different conclusions with regard to my own opinions on the respective issues.
With regard to illegal immigration, it is clear that prohibition does not work. It is also clear that it is in demand, since illegal immigrant workers find work quickly once in the USA.
There is a criminal network that supports illegal immigration, and it brings with it both violence and avoidance of government revenue through taxation.
One can argue that ending prohibition of migrant workers (essentially the situation we have, since legal immigration is extremely numbers-limited and by lottery for unskilled workers) would end the criminal organizations that support illegal immigration.
With regard to recreational drug use, it is also clear that prohibition does not work. It is likewise clear that such drugs are in demand, since they are quickly distributed and sold on the streets of America.
There is, as with illegal immigrants, a criminal network that supports drug importation and distribution. Likewise, it brings with it both violence and avoidance of government revenue through taxation.
Given that these two situation are quite similar, one might argue that both should be dealt with in a similar fashion. Logic would dictate that all things being equal, legalization in both cases would yield positive results.
And yet, I do not feel this way. I feel that prohibitions on immigration should be ended, and prohibitions on drugs should be continued.
There are many reasons I feel this way, some of the deeply personal (and some of you know to what I refer). However, I can summarize without getting too icky.
The first priority of any organized form of society is that it be able to survive. No society can condone activity inimical to its own survival and expect to survive.
So the question is not JUST whether or not legalizing illicit drugs and illegal immigration is the cost-effective and expedient thing to do, but ALSO whether or not such legalization would be ultimately destructive to society as a whole.
Many things which are legal are also destructive to society. Many things which are illegal are not that destructive overall. So I accept that there are no clear bright lines drawn, and that in many cases, there are both positive and negative effects on society for a given behavior or activity.
However, on balance, I do not see allowing the massive numbers of illegal workers who are already in the USA to remain on a legal basis as destructive of society. Detrimental, perhaps, but no more so than they are already. Drugs, on the other hand, I do see as quite destructive to society, and liable to increase that damage as they become legal and available. The increasing popularity of 'medical' marijuana in states such as California and Colorado, with the attendant popular wink-wink of declaring a medical 'problem' requiring the use of marijuana to alleviate pain, is proof enough of that to me. Illicit drug users do not care about anyone but themselves; their actions make that clear.
This is a deeply personal issue, and I'm not going to spend the next few days or weeks getting sucked into this thread to defend why I think recreational drug use is incredibly destructive to society; it is my opinion and although I strive to remain open-minded on most issues, on this particular issue I do not feel I will ever change my mind. I have a dim view of recreational drug use and not much respect for recreational drug users. For drug dealers, I would only wish we had a death penalty.
I feel that people who continue to buy illegal drugs for recreational use in the USA are knowingly supporting the criminal organizations that fund terrorism and crime cartels that pose significant risks to all Americans; and when they buy their pot in a baggie, they're essentially buying bullets for Al-Queda. Since they are willing to overlook that in order to get their high, I am willing to say that should be removed from society as a threat to us all. If they cannot control themselves to extend of forgoing their hobby in exchange for, say, fewer beheadings in Mexican border towns, then they're a danger to us all. Life behind bars would be fine with me. Yes, those organizations would vanish to a large extend if drugs were legal; but they are not. So continuing to buy from dealers is funding the criminals directly and indirectly funding terrorism. I can't comprehend how anyone considering themselves a good person can do that with a clear conscience except through denial.
Of course this means that I also support the status quo to some extent - continued prohibition of recreational drugs means continued criminal organizations to support the demand for illicit drugs. I accept that. However, although there is no solution to this problem that will work 100%, I feel that stronger enforcement against drug users and low-level dealers is a good start. Life in prison, capital punishment, and the like. Lock 'em up and execute the dealers. Won't cure the problem, but it will make it harder for the drug cartels to continue to operate as openly as they currently do.
Just my 2 cents.