I say this as someone who just had someone back into my car fairly hard and nearly strike someone in the process who was high as fuck:
Meh.
People shouldn’t drive or do a bunch of other things impaired. Obviously legal or not, people are going to do it. Though through education awareness campaigns, we might reduce things some.
But for as many social ills things like booze, weed, and smoking cause, making them illegal just seems to compound problems in other areas.