I guess that would make sense in a scientific paper or journal, but most people would have no idea what that means and just make for a confusing title that would turn people off from reading it. Almost everyone has heard of opiates in the evening news or social media.
And almost all those people have 'painkillers' such as paracetamol and ibuprofen in their cupboard, which they know not to be opiates.
The point isn't to accurately describe it as 'nociceptive' (which I've never heard of before either) and have that be understood, it's to qualify it such that it isn't confusing or sounding like an historical tale of how whatever the first NSAID/analgesic was came to be.
