FBI numbers do not include assault, domestic assault, burglary, kidnapping, carjacking, stalking, arson etc. as violent crimes. People are arrested for violent crimes much much more often than marijuana possession and it's not even close, and also only counts stats from 16,000 agencies which each count the data differently.
There were over 1 million arrests for Assault alone last year
Arrests by offense, age, and race
As for the Swiss, that model will not work in the U.S. It's easy to have rich folks pay for a few thousand other rich folks to shoot up free heroin and meth and pay for needles, etc. But there is nothing like that that could be done with our large diverse population, and not only will taxpayers refuse (and should) to support others' drug habits, the FDA, and physicians will not agree to administering something that will be that harmful to the patients, and US lawyers will sue as soon as the first patient/visitor overdose death would happen.
It's just not practical, not to mention that NO ONE PERSON ever gets out of drug addiction without wanting to as the first step, so you have the same issue of forcing them or else.