What Ross Bell and others call hysteria and short memory is actually for a not-insignificant number of people anger from long memory of people in the 'social concern' industry around cannabis. These people like my self now see them go hard to bat for the much worse alternative because its easier than admitting the often annoying marijuana legalisation advocates were essentially correct.
Getting Peter Dunne to admit that cannabis should be legal (which he voted against in 2006) rather than the synthetic-mimics he has enabled will never happen because it will involve him admitting he was wrong. For this and a number of other reasons he needs to retire from politics/be voted out.
In my daily life when the topic comes up I particularly enjoy stoking the dissonance between the fact cannabis is illegal and that some of these far worse and more addictive/agitative substances are legal. It is really easy to do and now strongly palatable to most of Middle Nuzilland that cannabis legalisation is the alternative/vastly preferable.
The class distinction between users of legal highs and cannabis is also pretty strong and easily made light of. Legal highs are now pretty much exclusively associated with bogan riff-raff who just literally need a hit to distract themselves from the reality of being socially/economically poor on these small islands while cannabis is well... a range of people from well-functioning to the depressed and in need of some social support. They range from connoisseurs and botanists to 'well, maybe a few times a year on new years day etc.'. Regardless, people almost universally recognise that the the harms are magnitudes less.
Whereas, the people producing and selling legal highs to the tunes of millions are goofy-rich white dudes who know how to order stuff from cheap foreign producers with the internet the best and market that shit. Very hard to defend or particularly like. It makes a select few rich.
Whereas, I have met more than a handful of young Maori boys in my life who come from family's deeply embedded in growing and selling Marijuana. Its what they know. I have encouraged them to stay on the narrow as close as possible until the day comes when Marijuana is legal and they could make themselves fine small-businessmen.