I agree with your thinking in the context of "keeping drug policy broadly the same but improving policing of it".

But fuck current drug policy. If someone is high on cannabis, or MDMA, or even "harder" drugs like cocaine and heroin, as long as it's not causing them to be violent or to commit other crimes such as theft then why should that become a legal problem for them any more than if they were intoxicated from spending a few hours drinking beers? And with the odd exception like keeping existing "driving under the influence" laws, we don't need dedicated "violent because of drugs" or "theft because of drugs" legislation, those crime should be treated the same regardless of whether drugs were involved or not.

The current "war on drugs" has been a failure at preventing people from buying and using recreational drugs, and it's been a failure at protecting society and members of society from themselves and from others, because evidence and experts all points towards better results coming from investing in being able to offer medical treatment services (rehab, therapy, etc) than policing and prison services.

I very much think there will come a time in the future, if we haven't accidentally killed our species by then, that we look back on this time the same way as most of us currently look at historic types of slavery, or stoning homosexuals to death, as both idiotic and incredible immoral. I hope we reach that point in the coming years/decades, rather than needing centuries.

(To be clear, I wrote "historic slavery" not to imply there are some forms of modern slavery that I think are OK; but because sadly there is still modern slavery ongoing all around the world, so we can't say that it's a universally condemned thing of the past. Hopefully one day it will be, too.)