What about discouraging wealth inequality and the lack of social support for the population in general? This would be a horrifying interference of the state in the dynamic of society, right?

But somehow for some people the state legislating about the behaviour of the average Joe to make sure he continues to be a well behaved cog is absolutely appropriate.

Maybe instead of taxing it to reduce its use, we can try making life better all around so people aren't incentivized to use it? Making other things more fun/accessible would decrease the time/availability for that behavior.

Why do you care what other people do with their private time?

In South Park, the real danger of cannabis is well explained: it may turn you into a couch potato, causing you to miss out on life instead of engaging in productive activities.

And South Park is the most realistic depiction of the clown world we are living in.