Making something legal does not introduce control. We still have alcoholics and smoking related health problems.
Citizen Khan is proposing decriminalisation of mild cannabis; not the more toxic Skunk strain.
If you are suggesting that something should be legal, because its use is widespread, then perhaps there should be no speed limits, parking fines etc.
The problem with modern weed is the increased potency: such as increasing the power of a car compared to the 60s, cannabis has increased many times the power of affect it has. Back in the day it really was Sweet (Mary-Jane), a subtle, fruity, flavour with a sweet aroma that was mild and mellow. Fast forward thirty years when Skunk appeared and it'd become a very different plant altogether: bitter, harsh with a rank odour.
Just as some folk want faster cars with more power, then they also demand a faster, higher hit...throw in the need for increased profit in a factory setting, rather than the cottage industry it once was, and the toxic affect on society overwhelms any area where it takes root.
Decriminalisation has shown it works, and nobody is proposing full legalisation.
