Legal or not, people will always take drugs
The logic seems to be that if someone does something harmful, it must be banned, irrespective of the number of people who take a substance and do not suffer serious ill-effects. Why should people not be allowed to take something because someone died? Despite the carnage on our roads, no one is advocating banning cars.
Any research about the detrimental effects of substances is useless unless we know the level of incidents vis-à-vis the numbers of people taking them. There was no research prior to the ban on magic mushrooms.