You can read all about the effects and side effects of strattera vs Adderall, welbutrin vs SSRI, but can you really know how these drugs feel unless you try them personally? I think that as long as there is medical clearance, a doctor should be able to "experiment" in a controlled/safe setting. I honestly think it would benefit patients.
It's definitely not completely crazy as an idea, and I can tell you that there are plenty of people working in the addiction community who are in recovery themselves (including many of the docs!). Some people might even argue that a doc in recovery understands what an addicted patient is going through way better than a doc like myself who has never had a substance use disorder.
One major problem with your proposal is that people's experiences with mind-altering drugs have a large element of subjectivity and idiosyncrasy to them. For example, some people who take ketamine think it's great and abuse it recreationally. Other people have horrible emergence reactions. I remember once telling a patient in the latter category that some people like to take this drug for fun, and her response to me was a vehement, "They're crazy!"
People also vary in terms of their risks of addiction and other substance use disorders. Plenty of people binge drink until they pass out every weekend, and not just college students. Many of them "grow out" of this behavior and eventually stop. Unfortunately, some of these people eventually progress into full-blown alcoholism. Why don't they all become alcoholics? It's a great question. Likewise, we really cannot predict in advance who is at risk of becoming an opioid addict if they take a Norco, and who isn't. We really don't understand why some people go on to progress to addiction, and others do not.
Given the risk of serious harm that can come from experimenting with mind-altering drugs, including addiction and SUD, I think that any benefits to be gained from hands-on experiential knowledge would likely be outweighed by the risks. Even knowing that I have pretty strong aversion reactions - I don't even like the feeling of being buzzed from alcohol - I would not want to take the risk personally. And I doubt too many of my colleagues who are in recovery themselves would be in favor of your proposal for exactly that reason.
P.S. You are probably already aware of the health issues that can come from abusing/misusing amphetamines like Adderall. If you weren't already aware of this, bupropion (or Wellbutrin) is a cathinone. Meaning, it's basically a legal "bath salt." Atomoxetine (Strattera) can cause psychosis and SI (not to mention CV events and sudden death). And, there is even a significant body of literature regarding possible withdrawal syndromes from SSRIs. Basically, the body adapts to whatever you do to it, and there is no free lunch out there when it comes to tweaking the mind, my friend.