Marijuana should be kept either decriminalized (but not fully legal) or criminalized depending on the state.
Majority of legislation to decriminalize/legalize marijuana recreationally do not recognized the threat of "modified" marijuana (marijuana with extra substances intending to enhance effects). Put someone high on that behind the wheel and they become a threat.
Totally inevitable of course, it's not like governments could have provided an an alternative alternative to dealers in exchange for regulations nipping their arms race in the bud in the first place.