Why do you consider that full legalization is making it easy for people to get the route to drug addiction?
In general, lack of availability is not a strong limiting factor even in countries with full criminalization; illegal drugs can be bought by anyone willing, there exists a market in any population center.
On the other hand, drugs being available in a controlled environment makes it easier to recover from addiction, and also limits the proliferation of various highly addictive chemicals which wouldn't be preferred or used by anyone if e.g. simpler opiates were available.
Saying that full legalization will cause a huge increase in drug addiction sounds plausible, but what evidence we have (e.g. Portugal decriminalization) shows that it doesn't really cause any disaster.
In general, lack of availability is not a strong limiting factor even in countries with full criminalization; illegal drugs can be bought by anyone willing, there exists a market in any population center.
On the other hand, drugs being available in a controlled environment makes it easier to recover from addiction, and also limits the proliferation of various highly addictive chemicals which wouldn't be preferred or used by anyone if e.g. simpler opiates were available.
Saying that full legalization will cause a huge increase in drug addiction sounds plausible, but what evidence we have (e.g. Portugal decriminalization) shows that it doesn't really cause any disaster.