That's less a manifestation of the drug than the personality of user. I've seen buck wild heroin addicts turn into model citizens when they know where their methadone is coming from every day. And half the bikers I know use meth and they not only manage to go on long formation rides without killing people they manage to hold on to their day jobs as well. Nobody is saying legalizing drugs is going to stop ambitious crackheads and methheads so you keep locking them up for the crimes they commit and try to rehab them while they're locked up.I don't believe cheaper prices and easier access will solve the other crimes associated with drug use.
Meth is cheap as hell. Meth heads are more likely than anyone to burglarized your house and steal your catalytic converter.
Besides the way we're doing it now has been an abject failure for 75 years, why not try it my way.