The issue with non-regulated dietary supplements may well be caused by the current state of regulation (this is strictly my own opinion/observation).

In the current state of things, we've grown accustomed to seeing warnings when the government thinks there is a potential danger with a particular FDA regulated drug. So perhaps the lack of warnings with supplements is giving people a false sense of security about the dietary supplements...ie, "if they were dangerous, surely there'd be a warning". If, as the parent comment suggests, the paradigm shifts so that the government's position is one of several factors to consider, perhaps then people would look at supplements with a greater degree of caution and suspicion. In other words, changing the paradigm may change people's behavior in terms of how they approach both drugs and supplements.