No, most opioid pain treatments have far more severe side effects than pot, and they tend to have a high risk of serious addiction that limits their dosage.
First, physical addiction is an issue, since the "proper dosage" to mitigate a particular patient's pain can easily be higher (or more frequent) than the "proper dosage" to avoid addiction; so on one hand some patients have to suffer without being able to increase the dose, and on the other hand the statistics show that even if in theory it "shouldn't be much of an issue", in practice addiction does happen.
But for the pure side effects, the most common issues are constipation and nausea. Then there's sedation (which may be comparable to effects of pot), and of course the suppressed breathing which makes accidental overdoses potentially deadly, unlike pot. Especially for chronic pain management, the long term effects add up, then you also risk liver damage, etc.
If you had a choice between taking heroin or pot, which one would you take? Granted prescription opiates are somewhat better than heroin, but not that much better.
Although, I suppose the side effects of pot are considered desirable by many.