Peoples reactions vary. I have personally known someone who, in spite of taking between 800 and 1200 mg of morphine a day for 10 years, not only had none of the issues you worry about but was able to quit, for several days with absolutely no withdrawal symptoms. She was taking it for pain management and wasn't quitting deliberately but because of our stupid and draconian laws concerning the drugs prescribing limitations.
Opium is far less addictive than morphine so it does not stand to reason that because a substantial number of morphine users experience addiction that an nearly equal number of opium users will also. There are not vast numbers of opium addicts today like there were in the past so we cannot say for certain what our society would look like were it to be legalized but we have no reason to imagine it would be any more harmful to society today than it was when it was legal. We can say that MOST addicts, if given the choice between opium or its far more debilitating relative heroin, would choose opium.
The specific biological impact you write of is very much a product of our society at least as much as it is our biology. When Laudanum was readily available and literally hundreds of thousands of people in this country were addicted the problems you associate as biologically inherent to opium by and large did not exist. When Laudanum was outlawed there was no surge in crime as addicts were all compelled to do whatever they needed to acquire more opium. Where were all the destroyed families because of Laudanum use? Please show me the destructive effects it had on our society in the first part of this century. Thousand of people just lazing about in laudanum dens wreaking havoc on the countries productivity and moral fiber!
There are hundreds of thousand of addicts like Rush Limbaugh who go to work everyday and no one knows they are addicts. The fact that our society makes it more difficult for addicts to hold down jobs tells us nothing about the addictive substance they use. In the 1950's it was extremely difficult for an openly homosexual man to hold down a job. Does this tell you anything about homosexuality?
The behavior habits of opium users are different than those of heroin users for both biological and societal reasons. You mention water. Opium is very much like water. Give a person all the water they want and they will be happy healthy and productive just as opium users were in the first part of this century. Deny someone access to either and how they might behave may be far more similar than you realize.
John Thornton