I think that was more of a linguistic change than anything. If the word "addiction" had been commonplace during the lead up to Prohibition, I bet you that the prohibitionist movement would have constantly used the term "alcohol addiction", despite alcohol use being ubiquitous. Nowadays, for example, you see articles talking about "caffeine addiction", despite the fact that the majority of the population drinks coffee.

I think you're absolutely right that "addiction" has a negative connotation, and all things considered most people are less likely to pass judgment on things that the majority does. But people do criticize popular things all the time too.

> But only now that everyone has stopped smoking do we actually talk about "smoking addiction."

Er, no, we started talking about nicotine addiction long before that.

> Back when everyone did it, it wasn't treated as an addiction with us blaming individual smokers for smoking.

Actually, treating it as an addiction has been exactly the opposite of "blaming individual smokers for smoking" -- while certainly the fact that it has become rarer has coincided with an increase in stigmatization (there's a two-way causal relationship there, in a positive feedback loop), that's separate entirely from treating it as an addiction (that's treating it as something people don't like around them.)

Treating it as an addiction is providing medical and counseling support for people to deal with the addiction, and placing blame on the tobacco companies for deceptively and knowingly marketing an addictive substance for many years.

> It was treated as a public health problem, and ultimately the blame was laid at the feet of the tobacco industry.

You seem to use "as an addiction" and "as a public health problem" as if they were opposites, which is odd, because actual addiction is (and is treated as) a fairly significant public health problems.