system
Given the following post, respond as if you're commenting on Reddit:
human
Why do doctors bother with painkillers like oxycodon, etc, that barely differ from morphine?

Specifically what I'm asking is why bother having so many different strong opiates if they all have very, very similar profiles? 


Besides duration, and the ceiling of the painkilling effects (i.e. codeine vs. morphine), the differences are very slight between these drugs. In fact I believe only morphine makes the WHO's list of essential medicines for a healthcare system. Why bother stocking all the rest? 


Edit:To add to this, I'm mostly interested in what, if any, implications the often slight alterations in morphine's analogues have that make them more desirable than morphine itself. Primarily I'm interested in how these small changes effect a drug's structure-activity relationship. Opiates are really just an ideal example I picked, if you know something regarding this in other kinds of drugs, that's also of help.


I am aware of the following points: Pharma pressures doctors to use new but not very innovative products, and that doctors like to rotate a person's pain medication to reduce tolerance effects.
gpt
While there are some differences within the group of opiods/opiates, you are right to question the clinical value of them.

Oxycodon may have a better metabolism (morphine has active metabolites and is more reliant on kidney function) and a more predictable bioavailability. 

In some surgical protocols you want a very short half-life (you might have continuous administration) which makes remifentanils pharmacological properties beneficial.

There are some opiods that have secondary effects, suchs as tramadol and tapentadol (monoaminergic reuptake inhibition).

There might also be a difference in documentation, for instance a pharmaceutical company might have been more willing to perform a study on a "new condition" using drugs that they still own - and we are more willing to use drugs with good studies backing them up. 

A very down to earth reason is that daily dosages of morphine in the 400 mg range ~~i.v.~~parenterally (with extra doses around 70 mg) evokes more worry than 80 mg of hydromorphone.