The trouble is the arbitrary nature of selectively enforcing laws. This is what leads to abuse of police power - if you don't know what laws are de facto ignored in your locale, or if the powers simply decide to change which ones they enforce, it's problematic.
Yes, there is a spectrum of "what is the best use of enforcement resources" - but that's why it falls into politics. I would argue that you did state the correct solution though: make sure the laws we have are the minimum set of necessary and sufficient. Don't try to "keep adjusting laws to track with consensus notions of justice" - keep the law set to the minimum and you don't have to keep adjusting things.
For instance - why do we have business license laws in the first place? I'd say get rid of them. Pay for the departments that are funded by licensing out of the general taxes. This will be a benefit to all - it will slightly lower barrier to entry to start a business. If you're worried about compliance: just roll this into liability law. Just make it so that if a business is in violation of environmental or OSHA or labor laws apply civil and criminal liability. Why have a need for both up-front licensing and liability law? I guess maybe I could see a need for having a business registry, but not necessarily a license.
I agree the above is simplistic, but for the sake of discussion it should convey the idea of streamlining regulations.
That would be ideal if the minimum were not variable, but it too is subject to shifts in public thought, and at some point of resistance to change we stop being robust to fleeting variations and start just not representing the public consensus, at which point we stop being a republic. Then, too, we have a legal system in which most of our
post ex facto adjustments to the enforcement of the law are exclusively mitigatory. In addition to our double jeopardy provisions, we don't have any way to anti-pardon people for conduct we agree should have been criminal in retrospect, and while I think we'd agree that such a system would be hugely abusable (and has been, in legal systems that have had it), it does mean that if we err on the side of too minimal a legal code, we have fewer tools available to us to correct after the fact than if we unintentionally convict people of crimes we don't want to punish them for.
As for why we have apparently frivolous laws like licensing, it's the same reason we have
malum prohibitum laws in the first place: so that laws can actually be protective without punishing people for things that haven't happened yet. Drunk driving isn't illegal because we think it's inherently wrong. It's illegal because we'd rather pull people off the road before they crash than charge them with vehicular manslaughter after the fact. Similarly, licensing laws exist in part to prevent people from evading other laws governing commercial conduct by claiming they're not actually operating a business or a specific kind of business; they're how you make a registry that people actually sign onto, and part of a whole constellation of codifying regulations. Disambiguating which laws apply to who up front saves a lot of time on the back end.
That's not to say these systems aren't abused or that regulations can't be streamlined, only that apparently superfluous laws can better serve the goals of the legal system than an absolutely minimal set of proscribed conduct by virtue of it only being possible to directly regulate past conduct.