I consider anything with a short history of human use, where the potential long-term effects are not yet known, to be an RC. That's a very broad category, however, and undoubtedly contains several subcategories like "hallucinogenic RC", "stimulant RC", "depressant RC", etc. 4fmp, for instance, is a stimulant, but because not much is known about it and there's no history of human use, it gets classed as an RC. With this "class" of drugs, it's absolutely vital to do your research (no pun intended) ahead of time, because not all RCs are created equal.
I envision that the ones with the highest potential for recreational use that the largest number of people find pleasurable will become more abundant over time, THEN there will be formal research done on their effects. Only when the propaganda machine spots a potential new "drug threat" will enough scientists, doctors, and chemists be prompted to study it further. I'm sure there's research being done on some of them now, but it takes a lot of different studies from a lot of different scientists to paint an accurate picture of the effects of a drug or anything else for that matter, and even then there are questions of bias and accuracy.
Until more is known about these drugs, WE are the researchers. The scientist and the guinea pig.