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Yes, things are slowly changing for the better, and in 20 years we will look at these laws as we look at prohibition.
But another problem here is that all individual cases are up to the prosecutors mostly, so if for example Baltimore gets different prosecutor that has different view on that, things might get bad again, and go in opposite direction.
So much safer way is decriminalisation of cannabis.
That's not accurate.
Cannabis extract without THC or with minimal amounts has became a widely available product. Eg "CBD".
Various state laws have been enacted now that require prosecutors to show an illegal %age of THC. Turns out labs don't have equipment to do that. The prosecutors are not just acting on a whim but based on their costs in getting that equipment or outsourcing and paying for those tests.
Prosecuting DAs are part of a self-propagating system that included the courts, the prosecuting and defending attorneys, and all the hapless victims. This system seeks fat profits. It's really all about the money not the law.
As for the way the law works, there is a federal law which become a "model statute" for the states. In the past if a state did not wish to adopt it or a harsher version of its own, the Fed would punish by withholding various funds.
Today that is not happening, a state is somewhat free to go against the federal MARIHUANA statutes, although not others.