By partisan, I mean arguing in favour of a cause.
"Using laws to change social norms is stupid, because it doesn't work without having serious negative consequences which outweigh any possible good results."
The cause you are arguing for here is some version of libertarianism. You are saying that government ought not to legislate to change social norms. You advance an argument that to do so is ineffective in all circumstances. Because you do not allow for any circumstances in which such legislation could work, your statement can reasonably be characterised as partisan and non-pragmatic. You can choose to take issue with some of that if you wish, but it does seem like a perfectly reasonable interpretation of what you wrote, even if it goes against the way you like to think of yourself, as some uber-rational and even-handed individual.
Your response to my mentioning DUIs shows that *you* have missed the point. At the time DUI laws were introduced, there was a social norm that said "it's perfectly fine to drive home after having had a beer or two". Such attitudes still exist in some places, such as parts of the British countryside. The laws were introduced to shift social attitudes. The reason legislators wanted those attitudes to shift was, as you say, because drinking causes a clear and present danger. But to be blind to the fact that the laws were introduced in the teeth of opposition claiming this was Nanny Statism and saying that attempts to shift social norms should be resisted is, well, silly. (On clear and present danger, smoking laws are contested precisely because this isn't the case, but they remain attempts to legislate to change social norms" and they have been pretty successful and the benefits in my view clearly outweigh the harms.)
I say again: it is perfectly reasonable for a government to introduce a law to shift a social norm, and it is possible to do so in a way that results in more benefit than harm. There are many examples of where this has happened.