So, I actually am a fan of your theory in this regard. I've come to believe that as we attempt to engineer better forms of medicine from plants, we can sometimes improve upon them, but we can also end up with stuff that is basically worse, an imitation of the real thing.
Take a look at Cannabis pharmaceuticals. It all seemed to be shaking out well back in my heyday, say 2008. There were pharmaceuticals that gave you the full Cannabis experience without having to smoke a plant, smell like weed, all that nonsense that we now take for granted due to legality. In the end, science has not been able to actually improve on the native, as-nature-made it Cannabis plant. To that effect, it's not even just the plant, it is indeed dozens, maybe fucking thousands of different substances in the plant from Terpenes to Cannabinoids to the undefined that has show, despite all predictions, that Cannabis is indeed the most effective form and we can indeed benefit from dozens, hundreds, thousands of different strains.
We have a guy with Back Pain who also needs to sleep. We have a guy with back pain who has a lot of work to get done, so with less sedation. Some people want weed purely for the anxiolysis and the physical effects are largely secondary, we have options for them too. It's truly amazing. Everything that I would have every predicted about this plant given my limited knowledge of pharmacy and chemistry was proven wrong basically.
With Opioids, it's obviously a little different. From the very start the name of the game was not the intricacie of the plant, but how can we boil this down to make it as potent and portable as possible. Perhaps Opium Poppies were the same. Subtle differences that could have been used for our benefit. It's like taking Cannabis, growin hemp, whatever is easiest to grow, and melting it down to THC.
With Morphine, I have to agree. For whatever reason, society gravitated toward DiacetylMorphine specifically. That is the one that won out over all others and it is such a small, small chemical distance from Morphine, basically making it more potent, that time and society would seem to implicate Morphine as one of the best. In that same vein, drugs that are closely related to Morphine like Hydromorphone (Dilaudid) and Oxymorphone (Opana; Numorphan) seem to often take the cake.
Meanwhile you have Pethidine (Demerol), Tramadol (Ultram) and Loperamide (Immodium) sitting at the loser's table. We engineered some novel new shit, but show me a true connoseeur of Opioids who prefers Fentanyl over Heroin and I'll show you a liar.
So, case in point, I definitely think what you're saying would make much sense. Morphine and Heroin were always my favorite. The Fentanyl epidemic practically did the leg work for me in reducing cravings for Opioids. It was great timing. They were so inferior that it was a different animal to me. It wasn't the same. It wasn't "magic" it was a sedative that took the sick away and its potent which is why it is such an obvious choice for the black market.